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Abstract:

A fuel cell stack system is configured to uniformly supply a fuel or an
electrolytic solution to each of fuel cell elements, and an electronic
device using the fuel cell stack system are provided. An electrolytic
solution channel allowing an electrolytic solution to flow therethrough
is arranged between a fuel electrode and an oxygen electrode, and a fuel
channel allowing a fuel to flow therethrough is arranged outside of the
fuel electrode. The electrolytic solution channels and the fuel channels
of all fuel cell elements are connected in series to one another. That
is, the fuel or the electrolytic solution emitted from an outlet of the
fuel channel or the electrolytic solution channel of one fuel cell
element enters into an inlet of the fuel channel or the electrolytic
solution channel of the next fuel cell element through a connection
channel. In addition, either or both of the electrolytic solution
channels and the fuel channels of some or all of the fuel cell elements
may be connected in series to one another.

Claims:

1-32. (canceled)

33. A fuel cell stack system comprising a plurality of fuel cell
elements, wherein the plurality of fuel cell elements each include a fuel
electrode and an oxygen electrode which are arranged so as to face each
other, and a channel enabling at least an electrolytic solution to flow
therethrough, and the channels of some or all of the plurality of fuel
cell elements are connected in series to one another.

34. The fuel cell stack system according to claim 33, wherein the
channels each include: an electrolytic solution channel arranged between
the fuel electrode and the oxygen electrode and enabling the electrolytic
solution to flow therethrough, and a fuel channel arranged on a side
opposite to a side where the oxygen electrode is arranged of the fuel
electrode and enabling a fuel to flow therethrough, and either or both of
the electrolytic solution channels and the fuel channels of some or all
of the plurality of fuel cell elements are connected in series to one
another.

35. The fuel cell stack system according to claim 34, wherein the fuel
channels of some or all of the plurality of fuel cell elements are
connected in series to one another, and the electrolytic solution
channels of all of the plurality of fuel cell elements are connected in
parallel to one another.

36. The fuel cell stack system according to claim 34, wherein the fuel
channels of all of the plurality of fuel cell elements are connected in
parallel to one another, and the electrolytic solution channels at least
of some of the plurality of fuel cell elements are connected in series to
one another.

37. The fuel cell stack system according to claim 34, wherein the fuel
channels and the electrolytic solution channels of at least some of the
plurality of fuel cell elements are connected in series to one another.

38. The fuel cell stack system according to claim 34, wherein either or
both of the electrolytic solution channels and the fuel channels of all
of the plurality of fuel cell elements are connected in series to one
another.

39. The fuel cell stack system according to claim 34, comprising: a
separation room removing carbon dioxide included in the fuel or the
electrolytic solution, or separating a fuel included in the electrolytic
solution.

40. The fuel cell stack system according to claim 34, wherein the
plurality of fuel cell elements each include a gas-liquid separation film
between the fuel channel and the fuel electrode.

41. A channel structure comprising: a first main channel connected to a
main inlet for fluid; a second main channel connected to a main outlet
for fluid; and two or more parallel channels arranged between the first
main channel and the second main channel and each having an inlet
connected to the first main channel and an outlet connected to the second
main channel, wherein one or more of the two or more parallel channels
each include a region of which the sectional area is reduced at either or
both of the inlet and the outlet.

42. The channel structure according to claim 41, wherein the region of
which the sectional area is reduced is arranged at the inlet.

43. The channel structure according to claim 41, wherein the region of
which the sectional area is reduced is arranged at the outlet.

44. The channel structure according to claim 41, wherein the sectional
areas of the first main channel and the second main channel are equal to
the sectional areas of the two or more parallel channels.

45. A fuel cell including an electrolyte between a fuel electrode and an
oxygen electrode, the fuel cell comprising: a fuel channel enabling a
fluid including a fuel to flow therethrough on a side opposite to a side
where the oxygen electrode is arranged of the fuel electrode, wherein the
fuel channel includes a first main channel connected to a main inlet for
the fluid, a second main channel connected to a main outlet for the
fluid; and two or more parallel channels arranged between the first main
channel and the second main channel and each having an inlet connected to
the first main channel and an outlet connected to the second main
channel, and one or more of the two or more parallel channels each
include a region of which the sectional area is reduced at either or both
of the inlet and the outlet.

46. The fuel cell according to claim 45, wherein an electrolytic solution
channel enabling a fluid including an electrolyte to flow therethrough is
arranged between the fuel electrode and the oxygen electrode, the
electrolytic solution channel includes a first main channel connected to
a main inlet for the fluid, a second main channel connected to a main
outlet for the fluid; and two or more parallel channels arranged between
the first main channel and the second main channel and each having an
inlet connected to the first main channel and an outlet connected to the
second main channel, and one or more of the two or more parallel channels
each include a region of which the sectional area is reduced at either or
both of the inlet and the outlet.

47. A fuel cell comprising an electrolytic solution between a fuel
electrode and an oxygen electrode, wherein either or both of the fuel
electrode and the oxygen electrode include a catalyst layer and a
functional layer arranged on the catalyst layer and preventing direct
contact between the catalyst layer and the electrolytic solution.

48. The fuel cell according to claim 47, wherein the functional layer is
arranged on the catalyst layer of the fuel electrode.

49. The fuel cell according to claim 47, wherein the functional layer is
arranged on the catalyst layer of the oxygen electrode.

50. The fuel cell according to claim 47, wherein the functional layer is
made of a porous material.

51. The fuel cell according to claim 47, wherein the functional layer is
made of an ion conductor.

52. The fuel cell according to claim 47, comprising: an electrolytic
solution channel arranged between the fuel electrode and the oxygen
electrode and enabling an electrolytic solution to flow therethrough, and
a fuel channel arranged on a side opposite to a side where the oxygen
electrode is arranged of the fuel electrode and enabling a fuel to flow
therethrough, wherein the functional layer is arranged on a surface on
the electrolytic solution side of the catalyst layer.

53. An electrode used as a fuel electrode or an oxygen electrode of a
fuel cell, the fuel cell including an electrolytic solution between the
fuel electrode and the oxygen electrode, the electrode comprising: a
catalyst layer; and a functional layer arranged on the catalyst layer and
preventing direct contact between the catalyst layer and the electrolytic
solution.

54. A channel structure comprising: a channel for fluid formed in a base;
and a fluid connector connected to the channel in a direction parallel to
a main surface of the base.

55. The channel structure according to claim 54, wherein the base is
formed by cutting a thin plate or bonding thin plates together, or
bonding flexible films together.

56. The channel structure according to claim 54, wherein the fluid
connector has a different sectional shape from the sectional shape of the
channel.

57. The channel structure according to claim 56, wherein the sectional
shape of the channel is rectangular, and the fluid connector is a
cylindrical tube.

58. The channel structure according to claim 54, wherein an end of the
channel is formed in a projection projected from a side surface of the
base in a direction parallel to a main surface of the base, the fluid
connector is connected to the projection, and a heat-shrinkable tube is
arranged on a connection part between the projection and the fluid
connector.

59. The channel structure according to claim 54, wherein an end of the
channel is formed in parallel with a side surface of the base, and is
connected to an auxiliary component including a curved channel curved at
90.degree. from the end of the channel therein, the fluid connector is
connected to the auxiliary component, and a heat-shrinkable tube is
arranged on a connection part between the auxiliary component and the
fluid connector.

60. The channel structure according to claim 54, wherein the base is a
micro total analysis system.

61. The channel structure according to claim 54, wherein the base is a
fuel cell.

62. An electronic device comprising a fuel cell stack system including a
plurality of fuel cell elements, wherein the plurality of fuel cell
elements each include a fuel electrode and an oxygen electrode which are
arranged so as to face each other, and a channel enabling at least an
electrolytic solution to flow therethrough, and the channels of some or
all of the plurality of fuel cell elements are connected in series to one
another.

63. An electronic device including a fuel cell, the fuel cell including
an electrolyte between a fuel electrode and an oxygen electrode, the
electronic device comprising: a fuel channel enabling a fluid including a
fuel to flow therethrough on a side opposite to a side where the oxygen
electrode is arranged of the fuel electrode, wherein the fuel channel
includes a first main channel connected to a main inlet of the fluid, a
second main channel connected to a main outlet of the fluid, and two or
more parallel channels arranged between the first main channel and the
second main channel and each having an inlet connected to the first main
channel and an outlet connected to the second main channel, and one or
more of the two or more parallel channels each include a region of which
the sectional area is reduced at either or both of the inlet and the
outlet.

64. An electronic device comprising a fuel cell including an electrolytic
solution between a fuel electrode and an oxygen electrode, wherein either
or both of the fuel electrode and the oxygen electrode include a catalyst
layer, and a functional layer arranged on the catalyst layer and
preventing direct contact between the catalyst layer and the electrolytic
solution.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a National Stage of International
Application No. PCT/JP2008/063650 filed on Jul. 30, 2008 and which claims
priority to Japanese Patent Application No. 2007-202006 filed on Aug. 2,
2007, Japanese Patent Application No. 2007-216397 filed on Aug. 22, 2007,
Japanese Patent Application No. 2007-231562 filed on Sep. 6, 2007, and
Japanese Patent Application No. 2007-236647 filed on Sep. 12, 2007, the
entire contents of which are being incorporated herein by reference.

BACKGROUND

[0002] The present disclosure relates to a fuel cell stack system such as
a direct methanol fuel cell (DMFC) directly supplying methanol to a fuel
electrode to cause a reaction, a fuel cell, an electrode used in the fuel
cell, and an electronic device using them. Moreover, the present
invention relates to a channel structure allowing a fluid (a liquid or a
gas) to flow therethrough, a fuel cell such as a DMFC using the channel
structure, and an electronic device including them. Further, the present
invention relates to a channel structure suitable for a micro TAS (Total
Analysis System), a fuel cell or the like.

[0003] Indicators of characteristics of a battery include energy density
and output density. The energy density is an amount of energy storage of
the battery per unit mass, and the output density is an output amount of
the battery per unit mass. Lithium-ion secondary batteries combine two
characteristics of relatively high energy density and remarkably high
output density, and also have high perfection, so it is widely adopted as
power sources for mobile devices. However, in recent years, the mobile
devices tend to consume more power with performance enhancement, thereby
further improvements in energy density and output density of the
lithium-ion secondary batteries are desired.

[0004] Solutions to such an issue include changing an electrode material
forming a cathode and an anode, improving a method of applying an
electrode material, improving a method of sealing an electrode material,
and the like, and research aimed at improving the energy density of the
lithium-ion secondary batteries has been conducted. However, a hurdle to
practical use is still high. Moreover, unless constituent materials used
for the lithium-ion secondary batteries are changed, it is difficult to
expect a drastic improvement in the energy density.

[0005] Therefore, the development of batteries with higher energy density
as an alternative to the lithium-ion secondary batteries is urgently
necessary, and fuel cells are considered as a promising candidate.

[0006] The fuel cell has a configuration in which an electrolyte is
arranged between an anode (a fuel electrode) and a cathode (an oxygen
electrode), and a fuel, and air or oxygen are supplied to the fuel
electrode and the oxygen electrode, respectively. As a result, an
oxidation-reduction reaction in which the fuel is oxidized by oxygen
occurs in the fuel electrode and the oxygen electrode, and a part of
chemical energy of the fuel is converted into electrical energy to be
extracted.

[0007] Various types of fuel cells have been already proposed or
prototyped, and some of them have been already put to practical use.
These fuel cells are classified into types, that is, an alkaline fuel
cell (AFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel
cell (MCFC), a solid electrolyte fuel cell (SOFC), a polymer electrolyte
fuel cell (PEFC) and the like according to electrolytes used in the fuel
cells. The PEFC is operable at a lower temperature than other types, for
example, a temperature of approximately 30° C. to 130° C.

[0008] As the fuel for the fuel cells, various flammable substances such
as hydrogen and methanol may be used. However, a gas fuel such as
hydrogen is necessary to be stored in a storage cylinder, so the gas fuel
is not suitable to size reduction. On the other hand, a liquid fuel such
as methanol is advantageous in terms of easy storage. Especially, the
DMFC does not need a reformer for extracting hydrogen from the fuel, so
the DMFC has advantages that its configuration is simplified and its size
is easily reduced.

[0009] In the DMFC, methanol as the fuel is typically supplied to the fuel
electrode as a high- or low-concentrated aqueous solution or as gaseous
pure methanol, and methanol is oxidized to carbon dioxide in a catalyst
layer of the fuel electrode. Protons produced at this time move to the
oxygen electrode through an electrolyte film separating the fuel
electrode and the oxygen electrode, and then react with oxygen in the
oxygen electrode, thereby to generate water. Reactions occurring in the
fuel electrode, the oxygen electrode and the whole DMFC are represented
by Chemical Formula 1.

[0010] (Chemical Formula 1)

[0011] Fuel electrode:
CH3OH+H2O→CO2+6e-+6H.sup.+

[0012] Oxygen electrode: (3/2)O2+6e-+6H.sup.+→3H2O

[0013] The whole DMFC: CH3OH+(3/2)O2→CO2+2H2O

[0014] The energy density of methanol as the fuel for the DMFC is
theoretically 4.8 kW/L, which is 10 or more times larger than the energy
density of a typical lithium-ion secondary battery. That is, the fuel
cell using methanol as a fuel has a good chance of exceeding the energy
density of the lithium-ion secondary battery. Therefore, among various
fuel cells, the DMFC is the most likely to be used as an energy source
for a mobile device, an electric vehicle or the like.

[0015] However, the DMFC has such an issue that even though its
theoretical voltage is 1.23 V, its output voltage when actually
generating electric power is reduced to approximately 0.6 V or less. A
cause of a reduction in output voltage is a voltage drop caused by
internal resistance of the DMFC, and the DMFC has internal resistance
such as resistance accompanied with reactions occurring in both
electrodes, resistance accompanied with movement of a substance,
resistance generated when protons moves through the electrolyte film and
further, contact resistance. Energy which is allowed to be actually
extracted as electrical energy through oxidation of methanol is
represented by a product of an output voltage during electric power
generation and the quantity of electric power flowing through a circuit,
so when the output voltage during electric power generation is reduced,
the energy which is allowed to be actually extracted is reduced
correspondingly. In addition, when the whole amount of methanol is
oxidized in the fuel electrode according to Chemical Formula 1, the
quantity of electric power which is allowed to be extracted to the
circuit through oxidation of methanol is proportional to the amount of
methanol in the DMFC.

[0016] Moreover, the DMFC has an issue of methanol crossover. Methanol
crossover is a phenomenon in which methanol reaches the oxygen electrode
side from the fuel electrode side through the electrolyte film due to two
mechanisms of a phenomenon in which methanol diffusively moves by a
difference in methanol concentration between the fuel electrode side and
the oxygen electrode side and an electroosmotic phenomenon in which
hydrated methanol is transported by the movement of water caused by the
movement of protons.

[0017] When methanol crossover occurs, methanol having passed through the
electrolyte film is oxidized in a catalyst layer of the oxygen electrode.
Although an oxidation reaction of methanol on the oxygen electrode side
is the same as the above-described oxidation reaction on the fuel
electrode side, the oxidation reaction on the oxygen electrode side
causes a reduction in the output voltage of the DMFC. Moreover, methanol
is not used for electric power generation on the fuel electrode side, and
is wasted on the oxygen electrode side, so the quantity of electric power
which is allowed to be extracted to the circuit is reduced
correspondingly. Further, the catalyst layer of the oxygen electrode is
not a platinum (Pt)-ruthenium (Ru) alloy catalyst but a platinum (Pt)
catalyst, so there is such an inconvenience that carbon monoxide (CO) is
easily absorbed onto a surface of the catalyst to cause catalyst
poisoning.

[0018] Thus, the DMFC has two issues of a reduction in voltage caused by
internal resistance and methanol crossover and fuel waste caused by
methanol crossover, and these issues cause a decline in electric power
generation efficiency of the DMFC. Therefore, to improve the electric
power generation efficiency of the DMFC, research and development aimed
at improving characteristics of materials forming the DMFC, and research
and development aimed at optimizing operating conditions of the DMFC have
been intensely conducted.

[0019] The research aimed at improving the characteristics of the
materials forming the DMFC includes research related to the electrolyte
film and a catalyst on the fuel electrode side. As the electrolyte film,
a polyperfluoroalkyl sulfonic acid-based resin film ("Nafion (a
registered trademark)" manufactured by E. I. du Pont de Nemours and
Company) is typically used; however, as an electrolyte film having higher
proton conductivity and a higher ability to prevent methanol from passing
through than the polyperfluoroalkyl sulfonic acid-based resin film, a
fluoropolymer film, a hydrocarbon-based polymer electrolyte film or a
hydrogel-based electrolyte film and the like have been studied. As the
catalyst on the fuel electrode side, research and development of a
catalyst having higher activity than a platinum (Pt)-ruthenium (Ru) alloy
catalyst which is typically used at present have been conducted.

[0020] Such an improvement in the characteristics of the constituent
materials of the fuel cell is appropriate as a means of improving the
electric power generation efficiency of the fuel cell. However, at
present, an optimum catalyst to solve the above-described two issues has
not yet been found, and an optimum electrolyte film has not yet been
found.

[0021] On the other hand, Japanese Unexamined Patent Application
Publication No. S59-191265 discloses a fuel cell using a liquid
electrolyte (an electrolytic solution) and not needing the electrolyte
film. The electrolytic solution may remain stationary between the oxygen
electrode and the fuel electrode, or the electrolytic solution may
circulate by flowing through a channel arranged between the oxygen
electrode and the fuel electrode to outside, and then going back to the
channel.

[0022] However, when a fuel cell stack system in which a plurality of fuel
cell elements are stacked in a vertical direction or a horizontal
direction is considered as a fuel cell using an electrolytic solution,
the fuel cell has issues that it is more difficult to manufacture the
fuel cell than a fuel cell including a solid electrolyte film in related
art, and it is difficult to stably generate electric power. It is because
unlike the fuel cell using the solid electrolyte film in related art, it
is necessary to supply two kinds of fluids, that is, a fuel and an
electrolytic solution as a liquid electrolyte to the fuel cell using the
electrolytic solution, and, further in the case where the fuel cell stack
system is configured, unless two kinds of fluids are supplied
substantially uniformly to each of the fuel cell elements, electric power
is not stably generated.

[0023] Typically, in the case where a fluid flows through the fuel cell
stack system, the fluid is sent to a main channel connected to all fuel
cell elements so as to be supplied to each of the fuel cell elements
through the channel. That is, the fluid is supplied by parallel
connection. However, it is extremely difficult to supply the fluid
uniformly to each of the fuel cell elements.

[0024] First, it is difficult to make the widths and heights of channels
of the fuel cell elements 100% uniform. In addition to this, carbon
dioxide or the like generated during electric power generation is
released into the fluid as bubbles, thereby to disturb the flow of the
fluid, so a pressure loss in each of the fuel cell elements is changed
due to various factors, thereby a fuel cell in which the fluid easily
flows and a fuel cell in which the fluid flows with difficulty are
inevitably produced. Means to prevent such a situation and create an
environment that the fluid easily flows include allowing a sufficient
height of the channel, and the like, but needless to say, this means
causes an increase in the thickness of the fuel cell stack system,
thereby resulting in an increase in size.

[0025] Also, Japanese Unexamined Patent Application Publication No.
2006-164872 discloses that a fluid is supplied to each fuel cell element
through an individual pump and a valve. However, in such a configuration
in related art, when a fuel cell stack system including 30 fuel cell
elements is assumed and two pumps are necessary per fuel cell, 60 pumps
are necessary in total. Therefore, devices for supply such as pumps
occupy a majority of the fuel cell stack system to cause an increase in
size of the fuel cell stack system, so the configuration is extremely
unrealistic.

[0026] Moreover, there is a common issue in a fuel cell needing an
electrolyte film and a fuel cell not needing an electrolyte film in
related art. For example, it is necessary to uniformly supply a fuel, an
electrolytic solution, or oxygen, air or the like into the fuel cell, and
when a flow rate distribution, a pressure distribution or a concentration
distribution is locally generated in the fuel cell, the characteristics
of the fuel cell is extremely unstable. Therefore, it is essential to
design an optimum shape of a channel (microchannel) so as to uniformly
supply a liquid or a gas supplied in the fuel cell as a whole.

[0027] As the shape of the channel of the fuel cell, there are a large
number of kinds such as a serpentine (meandering) shape type as one kind
of a serial channel in which an inlet 352A and an outlet 353A are
connected by one channel 356A as illustrated in FIG. 41 and a grid type
in which a grid-like channel 356B is arranged in a matrix form between
the inlet 352A and the outlet 353A as illustrated in FIG. 42. However,
the serpentine type channel shape has a major issue. It is because when a
gas fuel such as hydrogen or oxygen flows through the channel, the
pressure loss is small, but when a liquid fuel such as a methanol aqueous
solution or an electrolytic solution such as a sulfuric acid flows
through the channel, the pressure loss is pronouncedly increased to cause
an increase in the power of a pump for flowing the fluid.

[0028] Moreover, in the serpentine type channel, the case where the
concentration distribution of a reactive gas or a liquid tends to be
generated in the channel and electric power is generated locally under a
high utilization rate condition and a low utilization rate condition
often occurs, thereby the case tends to become a cause of reductions in
the performance and longevity of the fuel cell. That is, the
concentration distribution or the like causes catalyst deterioration,
thereby to reduce its performance not temporarily but permanently.

[0029] As a method of avoiding an increase in pressure loss and
deterioration in performance, the introduction of a parallel channel is
considered. In the parallel channel, as illustrated in FIG. 43, first,
the fluid flows from the inlet 352A to a first main channel 352 to be
supplied to a plurality of parallel channels 354 connected to the first
main channel 352 at a right angle, and then the fluid joins into a second
main channel 353 connected to the exit 353A. In such a parallel channel
configuration, compared to the serpentine type as one kind of serial
channel, the pressure loss is allowed to be significantly reduced.

[0030] However, in the channel configuration, it is extremely difficult to
supply the fluid uniformly to the plurality of parallel channels 354. In
particular, as illustrated in FIG. 43, in the case where the first main
channel 352 and the second main channel 353 have the same widths or
depths (heights) as those of the parallel channels 354, the fluid does
not flow uniformly through the parallel channels 354.

[0031] To allow the fluid to flow through the parallel channels 354 as
uniformly as possible, it is necessary to reduce the resistance of the
first main channel 352 connected to the inlet 352A and the resistance of
the second main channel 353 connected to the outlet 353A to the flow of
the fluid to a minimum, and to form a channel configuration where the
fluid flows more easily than the parallel channels 354. However, to do
so, it is necessary to allow a sufficient height of the channel, so the
thickness of a plate forming the channel is inevitably increased to 1 mm
or over. As a result, the thickness of the whole fuel cell is increased,
and the size of a stack configuration in which the fuel cells are stacked
is also increased.

[0032] Further, in the fuel cell using the electrolytic solution, the fuel
electrode and the oxygen electrode is constantly in contact with the
fluid, so there is an issue that deterioration in the electrodes such as
a crack or a hole is inevitable. The deterioration in the fuel electrode
promotes fuel crossover, and the deterioration in the oxygen electrode
causes leakage of the electrolytic solution. Such deterioration in the
electrodes is fatal, and the characteristics of the fuel cell are
pronouncedly deteriorated.

[0033] By the way, in related art, a fine channel formed on a glass
substrate or a base such as a plastic film is used as an analyzer, a
chemical reaction chip or a biochemistry chip or the like. As a method of
connecting a fluid connector (tube) to such a channel, for example, as
illustrated in FIG. 44, an extendable member 422 is arranged on an
inlet-outlet 431 of a channel 420, and a gap 440 between the inlet-outlet
421 and a fluid connector 430 is filled with the extendable member 422.
Moreover, Japanese Unexamined Patent Application Publication No.
2004-58214 discloses that a connection section having adhesion which is
fixable to another device is arranged around an opening of a channel.

[0034] However, in these configurations in related art, a tube is
connected in a direction perpendicular to a surface of the base, so a
space in a vertical direction of the base is occupied by connection of
the fluid connector, thereby the bases to which the fluid connectors are
connected are not allowed to be stacked in parallel.

[0035] There is a method in which the thickness of the base and the
thickness of the tube diameter of the fluid connector connected to the
base are substantially equal to each other, and the fluid connector is
connected to a side surface of the base with an adhesive or the like;
however, in addition to needing care for adhesion, the fluid connector is
not allowed to be connected to a substrate with a smaller thickness than
the tube diameter (outside diameter) of the fluid connector.

SUMMARY

[0036] A first object is to provide a fuel cell stack system allowing a
fuel or an electrolytic solution to be supplied uniformly to each fuel
cell element with a simple configuration, and an electronic device using
the fuel cell stack system.

[0037] A second object is to provide a channel structure allowing a fluid
to flow uniformly through parallel channels, and a fuel cell using the
channel structure, and an electronic device including them.

[0038] A third object is to provide a fuel cell allowed to prevent
deterioration of a fuel electrode or an oxygen electrode, an electrode,
and an electronic device using the electrode.

[0039] A fourth object is to provide a channel structure allowed to reduce
a space for connection of a fluid connector.

[0040] A fuel cell stack system according to an embodiment includes a
plurality of fuel cell elements, in which the plurality of fuel cell
elements each include a fuel electrode and an oxygen electrode which are
arranged so as to face each other, and a channel allowing at least an
electrolytic solution to flow therethrough, and the channels of some or
all of the plurality of fuel cell elements are connected in series to one
another.

[0041] Here, "connected in series" means that an outlet of the fuel
channel or the electrolytic solution channel of one fuel cell element is
connected to an inlet of the fuel channel or the electrolytic solution
channel of the next fuel cell element. In addition, "connected in
parallel" means that there is a main channel connected to all of the fuel
cell elements, and the main channel is divergently connected to an inlet
of the fuel channel or the electrolytic solution channel of each fuel
cell element.

[0042] In the fuel cell stack system of an embodiment, the channels of
some or all of the plurality of fuel cell elements are connected in
series to one another, so the number of supply auxiliaries such as pumps
or valves is reduced, thereby the configuration is simplified. Moreover,
influences such as nonuniformity of the flow of fluid through each of the
fuel cell elements, a change in pressure loss, internal characteristics
and the like are reduced, and the fuel or the electrolytic solution is
uniformly supplied to each of the fuel cell elements. Therefore,
stability of electric power supply is improved.

[0043] A first electronic device according to an embodiment includes a
fuel cell stack system including a plurality of fuel cell elements, and
the fuel cell stack system is configured of the above-described fuel cell
stack system of the invention.

[0044] In the first electronic device of the embodiment, the fuel cell
stack system according to the above-described embodiment allowing stable
electric power generation is included, so even if the number of fuel cell
elements is increased, stable electric power generation is allowed, and
the first electronic device is allowed to respond to more functions and
higher performance with an increase in electric power consumption.

[0045] A first channel structure according to the embodiment includes a
first main channel connected to a main inlet for fluid; a second main
channel connected to a main outlet for fluid; and two or more parallel
channels arranged between the first main channel and the second main
channel and each having an inlet connected to the first main channel and
an outlet connected to the second main channel, in which one or more of
the two or more parallel channels each include a region of which the
sectional area is reduced at either or both of the inlet and the outlet.

[0046] In the first channel structure of the embodiment, a fluid enters
from the main inlet to the first main channel, and then enters from the
first main channel to the inlets of the parallel channels to flow through
the parallel channels, and the fluid enters from the outlets of the
parallel channels to the second main channel to exit from a main outlet.
Here, the region of which the sectional area is reduced is arranged at
either or both of the inlet and the outlet of one or more of the parallel
channels, so the region becomes a barrier to the flow of the fluid, and
the resistance of the first main channel or the second main channel to
the flow is reduced to cause easy flow of the fluid, and uniformity of
the flow of the fluid through the parallel channels is improved.

[0047] A first fuel cell of an embodiment including an electrolyte between
a fuel electrode and an oxygen electrode includes: a fuel channel
allowing a fluid including a fuel to flow therethrough on a side opposite
to a side where the oxygen electrode is arranged of the fuel electrode,
in which the fuel channel includes a first main channel connected to a
main inlet for the fluid, a second main channel connected to a main
outlet for the fluid; and two or more parallel channels arranged between
the first main channel and the second main channel and each having an
inlet connected to the first main channel and an outlet connected to the
second main channel, and one or more of the two or more parallel channels
each include a region of which the sectional area is reduced at either or
both of the inlet and the outlet.

[0048] In the first fuel cell of the embodiment, the channel structure
according to the above-described embodiment is included as the fuel
channel, so the fluid including the fuel uniformly flows through the
parallel channels. Therefore, when the number of parallel channels is
increased, an output is increased with a linear relationship, and
electric power characteristics are improved.

[0049] A second electronic device of the embodiment includes a fuel cell
including an electrolyte between a fuel electrode and an oxygen
electrode, and the fuel cell is configured of the above-described first
fuel cell of the embodiment.

[0050] In the second electronic device according to the embodiment, the
fuel cell of the embodiment with improved electric power generation
characteristics is included, so the second electronic device is allowed
to respond to more functions and higher performance with an increase in
electric power consumption.

[0051] A second fuel cell according to the embodiment includes an
electrolytic solution between a fuel electrode and an oxygen electrode,
in which either or both of the fuel electrode and the oxygen electrode
include a catalyst layer and a functional layer arranged on the catalyst
layer and preventing direct contact between the catalyst layer and the
electrolytic solution.

[0052] An electrode according to the embodiment is used as a fuel
electrode or an oxygen electrode of a fuel cell including an electrolytic
solution between the fuel electrode and the oxygen electrode, and
includes a catalyst layer; and a functional layer arranged on the
catalyst layer and preventing direct contact between the catalyst layer
and the electrolytic solution.

[0053] A third electronic device according to the embodiment includes a
fuel cell including an electrolytic solution between a fuel electrode and
an oxygen electrode, and the fuel cell is configured of the
above-described second fuel cell of the invention.

[0054] In the second fuel cell of the embodiment or the electrode of the
embodiment, as the functional layer preventing direct contact between the
catalyst layer and the electrolytic solution is arranged on the catalyst
layer, the occurrence of deterioration such as a crack or a hole in the
fuel electrode or the oxygen electrode is prevented. Therefore, fuel
crossover due to deterioration of the fuel electrode, the leakage of the
electrolytic solution due to the deterioration of the oxygen electrode,
and the like is reduced, and stable characteristics are maintained, and
long-time electric power generation is allowed.

[0055] In the third electronic device of the embodiment, the second fuel
cell according to the above-described embodiment allowed to generate
electric power for a long time is included, so the third electronic
device is allowed to respond to more functions and higher performance
with an increase in electric power consumption.

[0056] A second channel structure of the embodiment includes a channel for
fluid formed in a base; and a fluid connector connected to the channel in
a direction parallel to a main surface of the base. Here, "main surface
of the base" is a flat surface in the case where the base is a thin plate
made of glass, silicon (Si) or the like, but is not necessarily a flat
surface, and, for example, in the case where the base is configured of a
flexible film, the main surface may be a flat surface or a curved
surface.

[0057] According to the fuel cell stack system of the embodiment, the
channels of some or all of the plurality of fuel cell elements are
connected in series to one another, so the number of supply arbitraries
such as pumps or valves is allowed to be reduced, and the configuration
is allowed to be simplified. Moreover, influences such as nonuniformity
of the flow of fluid through each of the fuel cell elements, a change in
pressure loss, and internal characteristics are allowed to be reduced,
and the fuel or the electrolytic solution is allowed to be uniformly
supplied to each of the fuel cell elements. Therefore, the stability of
electric power generation is allowed to be improved, and the fuel cell
stack system is suitable for a multifunctional high-performance
electronic device consuming a large amount of electric power.

[0058] According to the first channel structure of the embodiment, the
region of which the sectional area is reduced is arranged at either or
both of the inlet and the outlet of one or more of two or more parallel
channels, so the fluid is allowed to uniformly flow through the parallel
channels. Therefore, when the channel structure is applied to a fuel
channel of a fuel cell, or the like, the fluid including the fuel is
allowed to uniformly flow through the parallel channels, and electric
power characteristics are allowed to be improved, and the fuel channel is
suitable for a multifunctional high-performance electronic device
consuming a large amount of electric power.

[0059] According to the second fuel cell of the embodiment or the
electrode of the embodiment, the functional layer preventing direct
contact between the catalyst layer and the electrolytic solution is
arranged on the catalyst layer, deterioration such as a crack or a hole
in the fuel electrode or the oxygen electrode is preventable. Therefore,
a decline in characteristics of the fuel cell is preventable, and
long-time electric power generation is allowed, and they are suitable for
a multifunctional high-performance electronic device consuming a large
amount of electric power.

[0060] According to the second channel structure of the embodiment, the
fluid connector is connected to the channel formed in the base in a
direction parallel to the main surface of the base, so a space in a
vertical direction of the base is not occupied by connection of the fluid
connector. Therefore, a space for connection of the fluid connector is
allowed to be reduced, and the bases where the fluid connector is
connected are allowed to be stacked in parallel, thereby integration is
allowed to be improved.

[0061] Additional features and advantages are described herein, and will
be apparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

[0062] FIG. 1 is an illustration of a schematic configuration of an
electronic device including a fuel cell stack system according to a first
embodiment.

[0063]FIG. 2 is an illustration of configurations of two fuel cell
elements in a fuel cell stack system illustrated in FIG. 1.

[0064]FIG. 3 is an illustration of another connection example of an
electrolyte channel and a fuel channel.

[0065] FIG. 4 is an illustration of still another connection example of
the electrolyte channel and the fuel channel.

[0066] FIG. 5 is an illustration of a further connection example of the
electrolyte channel and the fuel channel.

[0067]FIG. 6 is an illustration of a still further connection example of
the electrolyte channel and the fuel channel.

[0068]FIG. 7 is an illustration of a still connection example of the
electrolyte channel and the fuel channel.

[0069] FIG. 8 is an illustration of a schematic configuration of an
electronic device including a fuel cell system according to a second
embodiment.

[0070]FIG. 9 is a sectional view illustrating a configuration of a fuel
cell illustrated in FIG. 8.

[0071] FIG. 10 is a perspective view illustrating an outer appearance of a
fuel channel illustrated in FIG. 9.

[0072] FIG. 11(A) is a plan view illustrating a configuration of the fuel
channel illustrated in FIG. 10 when viewed from a side where a first main
channel, a second main channel and parallel channels are arranged, FIG.
11(B) is a sectional view taken along a line XIB-XIB of FIG. 11(A), and
FIG. 11(C) is a sectional view illustrating a configuration of a rib in
one parallel channel.

[0073] FIG. 12 is a perspective view illustrating an outer appearance of
an electrolytic solution channel illustrated in FIG. 9.

[0074]FIG. 13(A) illustrates a configuration of the electrolyte channel
illustrated in FIG. 12 when viewed from a side where a first main
channel, a second main channel and parallel channels are arranged, FIG.
13(B) is a sectional view taken along a line XIIIB-XIIIB of FIG. 13(A),
and FIG. 13(C) is a sectional view illustrating a configuration of a rib
in one parallel channel.

[0075]FIG. 14 is an illustration of a configuration of a fuel cell of a
fuel cell system according to a third embodiment.

[0076]FIG. 15 is an illustration of a modification example of the fuel
cell illustrated in FIG. 14.

[0077]FIG. 16 is an illustration of another modification example of the
fuel cell illustrated in FIG. 14.

[0078]FIG. 17 is an illustration of a configuration of a fuel cell
according to a fourth embodiment.

[0079] FIG. 18 is a sectional view illustrating a configuration of a
channel structure according to a fifth embodiment.

[0080]FIG. 19 is a plan view illustrating a configuration of the channel
structure illustrated in FIG. 18.

[0081]FIG. 20 is a perspective view illustrating an example of an
exploded configuration of the channel structure illustrated in FIGS. 18
and 19.

[0082] FIG. 21 is a perspective view illustrating another example of the
exploded configuration of the channel structure illustrated in FIGS. 18
and 19.

[0083] FIG. 22 is a sectional view illustrating a configuration of a
channel structure according to a modification example of the embodiment.

[0084] FIG. 23 is an exploded perspective view illustrating a
configuration of an auxiliary component illustrated in FIG. 22.

[0085] FIG. 24 is a sectional view illustrating a configuration of a fuel
cell in which a fuel channel is configured of the channel structure
illustrated in FIGS. 18 and 19.

[0086]FIG. 25 is a sectional view illustrating a configuration of a fuel
cell in which a fuel channel and an electrolytic solution channel each
are configured of the channel structure illustrated in FIGS. 18 and 19.

[0091]FIG. 30 is a plot illustrating a result of Comparative Example 1.

[0092] FIG. 31 is a plot illustrating a result of Example 4.

[0093] FIG. 32 is a plot illustrating a result of Comparative Example 2.

[0094] FIG. 33 is a plot illustrating a result of Example 5.

[0095]FIG. 34 is an illustration of configurations of two fuel cell
elements of a fuel cell stack system according to a modification example.

[0096]FIG. 35 is an illustration of configurations of two fuel cell
elements of the fuel cell stack system according to a modification
example.

[0097]FIG. 36 is a plan view and a sectional view illustrating a
modification example of the fuel channel illustrated in FIG. 11.

[0098] FIG. 37 is a plan view and a sectional view illustrating another
modification example of the fuel channel illustrated in FIG. 11.

[0099]FIG. 38 is a sectional view illustrating a modification example of
the rib illustrated in FIG. 11(C).

[0100] FIG. 39 is a sectional view illustrating a modification example of
the fuel cell illustrated in FIG. 9.

[0101]FIG. 40 is a sectional view illustrating another modification
example of the fuel cell illustrated in FIG. 9.

[0102]FIG. 41 is a plan view illustrating an example of a channel in
related art.

[0103]FIG. 42 is a plan view illustrating another example of the channel
in related art.

[0104]FIG. 43 is a plan view illustrating still another example of the
channel in related art.

[0105] FIG. 44 is an illustration for describing a method of connecting a
fluid connected to the channel in related art.

DETAILED DESCRIPTION

[0106] Embodiments will be described in detail below.

[0107] (First Embodiment)

[0108] FIG. 1 illustrates a schematic configuration of an electronic
device including a fuel cell stack system according to a first
embodiment. The electronic device is a small- to large-sized device
needing electric power, for example, a mobile device such as a cellular
phone or a PDA (Personal Digital Assistant), a notebook PC (Personal
Computer), a camera, or a vehicle, and the electronic device includes a
fuel cell stack system 1 and an external circuit (load) 2 driven by
electrical energy generated in the fuel cell stack system 1.

[0109] The fuel cell stack system 1 includes, for example, a fuel cell
stack 110, a measurement section 120 measuring the operating state of the
fuel cell stack 110, and a control section 130 determining operating
conditions of the fuel cell stack 110 based on a measurement result by
the measurement section 120. The fuel cell stack system 1 also includes,
for example, an electrolyte supply section 140 supplying, for example, a
sulfuric acid as an electrolytic solution F1 to the fuel cell stack 110,
and a fuel supply section 140 supplying, for example, methanol as a fuel
F2 to the fuel cell stack 110. When the electrolyte is supplied as a
fluid in such a manner, an electrolyte film is not necessary, and
electric power is allowed to be generated without influences of
temperature and humidity, and compared to a typical fuel cell using the
electrolyte film, ionic conductivity (proton conductivity) is allowed to
be improved. Moreover, risks such as deterioration of the electrolyte
film or a decline in proton conductivity caused by dryness of the
electrolyte film are eliminated, and issues such as flooding and moisture
control in an oxygen electrode are solvable.

[0110] The fuel cell stack 110 is configured by stacking a plurality of
(for example, four in FIG. 1) fuel cell elements 111 in a vertical
direction (a stacking direction). FIG. 2 illustrates configurations of
two fuel cell elements 111 (111A and 111B) of the fuel cell stack 110
illustrated in FIG. 1. The fuel cell elements 111 are so-called direct
methanol flow based fuel cells (DMFFC), and each have a configuration in
which a fuel electrode (anode) 10 and an oxygen electrode (cathode) 20
are arranged so as to face each other. An electrolytic solution channel
30 allowing the electrolytic solution F1 to flow therethrough is arranged
between the fuel electrode 10 and the oxygen electrode 20. A fuel channel
40 allowing the fuel F2 to flow therethrough is arranged on the outside
of the fuel electrode 10, that is, a side opposite to a side where the
oxygen electrode 20 is arranged.

[0111] The fuel electrode 10 has a configuration in which a catalyst layer
11, a diffusion layer 12 and a current collector 13 are stacked in order
from the oxygen electrode 2 side, and is contained in an external member
14. Moreover, the fuel electrode 10 also has a function as a separation
film separating the electrolytic solution F1 and the fuel F2, and is
allowed to prevent crossover so as to obtain high energy density. The
oxygen electrode 20 has a configuration in which a catalyst layer 21, a
diffusion layer 22 and a current collector 23 are stacked in order from
the fuel electrode side, and is contained in an external member 24. In
addition, air, that is, oxygen is supplied to the oxygen electrode 20
through the external member 24.

[0112] The catalyst layers 11 and 21 are made of, for example, a simple
substance or an alloy of metal such as palladium (Pd), platinum (Pt),
iridium (Ir), rhodium (Rh), ruthenium (Ru) or the like as a catalyst.
Moreover, the catalyst layers 11 and 21 may include a proton conductor or
a binder in addition to the catalyst. As the proton conductor, the
above-described polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a
registered trademark)" manufactured by E. I. du Pont de Nemours and
Company) or other resins having proton conductivity are cited. The binder
is added to maintain the strength or flexibility of the catalyst layers
11 and 21, and as the binder, for example, a resin such as
polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) is
cited.

[0113] The diffusion layers 12 and 22 are configured of, for example, a
carbon cloth, a carbon paper or a carbon sheet. The diffusion layers 12
and 22 are preferably subjected to water-repellent treatment by
polytetrafluoroehylene (PTFE).

[0114] The current collectors 13 and 23 are configured of, for example, a
titanium (Ti) mesh.

[0115] The external members 14 and 24 have, for example, a thickness of
2.0 mm, and are made of a commonly available material such as a titanium
(Ti) plate or an acid-resistant metal plate, but the material is not
specifically limited thereto. The external members 14 and 24 are
preferably as thin a thickness as possible.

[0116] The electrolytic solution channel 30 and the fuel channel 40 are,
for example, fine channels formed by processing a resin sheet, and are
adhered to the fuel electrode 10. In addition, the number of the channels
is not limited. The widths, heights and lengths of the channels are not
specifically limited, but they are preferably small.

[0117] The electrolytic solution channels 30 and the fuel channels 40 of
all of four fuel cell elements 111 are connected in series to one
another. Thereby, in the fuel cell stack system 1, the fuel F2 or the
electrolytic solution F1 is allowed to be uniformly supplied to each of
the fuel cell elements 111 with a simple configuration.

[0118] More specifically, in each of the fuel cell elements 111, an
electrolytic solution inlet 24A and an electrolytic solution outlet 24B
are arranged in the external member 24. The electrolytic solution inlet
24A of a first fuel cell element 111A is connected to an electrolytic
solution supply section 140 (not illustrated in FIG. 2, refer to FIG. 1),
and the electrolytic solution outlet 24B is connected to the electrolytic
solution inlet 24A of the next fuel cell element 111B through a
connection channel 24C. Therefore, the electrolytic solution inlet 24A of
the first fuel cell element 111 and the electrolytic solution outlet 24B
of a last fuel cell element 111 are connected to the electrolytic
solution supply section 140, and the electrolytic solution inlet 24A of
each of other fuel cell elements 111 is connected to the electrolytic
solution outlet 24B of a fuel cell element 111 previous thereto. Thereby,
the electrolytic solution channels 30 of all fuel cell elements 111 are
connected in series to one another, and the electrolytic solution F1
supplied from the electrolytic solution supply section 140 enters the
electrolytic solution inlet 24A of the first fuel cell element 111A, and
exits from the electrolytic solution outlet 24B of the first fuel cell
element 111A to enter the electrolytic solution inlet 24A of the next
fuel cell element 111B, and after the electrolytic solution F1 flows
through all of the fuel cell elements 111 in the same manner, the
electrolytic solution F1 exits from the electrolytic solution outlet 24B
of the last fuel cell element 111 to return to the electrolytic solution
supply section 140.

[0119] Moreover, in each of the fuel cell elements 111, a fuel inlet 14A
and a fuel outlet 14B are arranged in the external member 14. The fuel
inlet 14A of a first fuel cell element 111A is connected to the fuel
supply section 150 (not illustrated in FIG. 2, refer to FIG. 1), and the
fuel outlet 14B is connected to the fuel inlet 14A of the next fuel cell
element 111B through a connection channel 14C. Therefore, the fuel inlet
14A of the first fuel cell element 111 and the fuel outlet 14B of a last
fuel cell element 111 are connected to the fuel supply section 150, and
the fuel inlet 14A of each of other fuel cell elements 111 is connected
to the fuel outlet 14B of a fuel cell element 111 previous thereto.
Thereby, the fuel channels 40 of all fuel cell elements 111 are connected
in series to one another, and the fuel F2 supplied from the fuel supply
section 150 enters the fuel inlet 14A of the first fuel cell element
111A, and exits from the fuel outlet 14B of the first fuel cell element
111A to enter the fuel inlet 14A of the next fuel cell element 111B, and
after the fuel F2 flows through all of the fuel cell elements 111 in the
same manner, the fuel F2 exits from the outlet 14B of the last fuel cell
element 111 to return to the fuel supply section 150.

[0120] The fuel inlets 14A and the fuel outlets 14B, and the electrolytic
solution inlets 24A and the electrolytic solution outlets 24B may be
configured of, for example, joints made of a resin or channels formed by
bonding a resin sheet having adhesion together. In the former case, the
connection channels 14C and 24C may be configured of silicone tubes. In
the latter case, the connection channels 14C and 24C may be configured of
channels formed by bonding a resin sheet having adhesion together. In
addition, the electrolytic solution inlets 24A and the electrolytic
solution outlets 24B, and the fuel inlets 14A and the fuel outlets 14B
are not necessarily formed in the external members 24 and 14,
respectively, and may be arranged in only one of the external member 24A
and the external member 14A. In this case, an internal channel
configuration allows the electrolytic solution F1 and the fuel F2 to be
distributed to the electrolytic solution channel 30 and the fuel channel
40, respectively.

[0121] A separation room is arranged in each of the connection channels
24C and 14C. As there is a possibility that a diffused fuel (methanol),
carbon dioxide bubbles generated in the fuel electrode 10, or the like
are contained in the electrolytic solution F1 emitted from the
electrolytic solution outlet 24B, the separation room 160 arranged in the
connection channel 24C removes such carbon dioxide or separates the fuel.
As there is a possibility that carbon dioxide bubbles generated in the
fuel electrode 10 or the like are contained in the fuel F2 emitted from
the fuel outlet 14B, the separation room 160 arranged in the connection
channel 14C removes carbon dioxide. A methanol separation mechanism is
configured of, for example, a filter, or a mechanism removing methanol by
burning, reacting or evaporating methanol. A mechanism removing carbon
dioxide is configured of, for example, a mechanism removing carbon
dioxide by a filter or reacting carbon dioxide. In addition, the
separation room 160 is not necessarily arranged in each of the connection
channels 24C and 14C, and may be arranged on a top surface, a bottom
surface or a side surface of each of the fuel cell elements 111.

[0122] The plurality of fuel cell elements of the fuel cell stack 110 are
electrically connected to one another in series or depending on
specifications, in parallel. When electric power is repeatedly generated
in the fuel cell stack 110, deterioration of the fuel cell elements 111
occurs. Moreover, the fuel cell elements 111 vary slightly in
characteristics without exception, so a fuel cell element 111 which is
easily deteriorated and a fuel cell element 111 which is resistant to
deterioration are produced. Therefore, to continuously generate electric
power in the fuel cell stack 110 even under such circumstances, the fuel
cell stack 110 preferably has an electrical circuit configuration in
which when the fuel cell element 111 which is not at all allowed to
contribute to electric power generation due to deterioration is produced,
the fuel cell stack 110 terminates electrical connection to the fuel cell
element 111, and establishes direct connection to the next fuel cell
element 111.

[0123] The measurement section 120 illustrated in FIG. 1 measures the
operating voltage and the operating current of the fuel cell stack 110,
and includes, for example, a voltage measurement circuit 121 measuring
the operating voltage of the fuel cell stack 110 and a current
measurement circuit 122 measuring the operating current, and a
communication line 123 for transmitting an obtained measurement result to
the control section 130.

[0124] The control section 130 illustrated in FIG. 1 controls an
electrolyte supply parameter and a fuel supply parameter as the operating
conditions of the fuel cell stack 110 based on the measurement result
from the measurement section 120, and includes, for example, a computing
section 131, a storage (memory) section 132, a communication section 133
and a communication line 134. Here, the electrolyte supply parameter
contains, for example, the supply flow velocity of the electrolytic
solution F1. The fuel supply parameter contains, for example, the supply
flow velocity and the supply amount of the fuel F2, and may contain a
supply concentration, if necessary. The control section 130 may be
configured of, for example, a microcomputer.

[0125] The computing section 131 calculates the output of the fuel cell
stack 110 from the measurement result obtained by the measurement section
120 so as to set the electrolyte supply parameter and the fuel supply
parameter. More specifically, the computing section 131 calculates the
averages of anode potentials, cathode potentials, output voltages and
output currents sampled from various measurement results inputted into
the storage section 132 at regular intervals to obtain an average anode
potential, an average cathode potential, an average output voltage and an
average output current, and then input them into the storage section 132,
and intercompares various average values stored in the storage section
132 to determine the electrolyte supply parameter and the fuel supply
parameter.

[0126] The storage section 132 stores various measurement values
transmitted from the measurement section 120, various average values
calculated by the computing section 131, and the like.

[0127] The communication section 133 has a function of receiving the
measurement result from the measurement section 120 through the
communication line 123 to input the measurement result to the storage
section 132, and a function of outputting signals setting the
electrolytic solution supply parameter and the fuel supply parameter to
the electrolytic solution supply section 140 and the fuel supply section
150, respectively, through the communication line 134.

[0128] The electrolytic solution supply section 140 illustrated in FIG. 1
includes an electrolytic solution storage section 141, an electrolytic
solution supply adjustment section 142 and an electrolytic solution
supply line 143. The electrolytic solution storage section 141 stores the
electrolytic solution F1, and is configured of, for example, a tank or a
cartridge. The electrolytic solution supply adjustment section 142
adjusts the supply flow velocity of the electrolytic solution F1. The
electrolytic solution supply adjustment section 142 may be configured of
any component which is allowed to be driven by a signal from the control
section 130, and is not specifically limited, but the electrolytic
solution supply adjustment section 142 is preferably configured of, for
example, a valve driven by a motor or a piezoelectric device or an
electromagnetic pump.

[0129] The fuel supply section 150 illustrated in FIG. 1 includes a fuel
storage section 151, a fuel supply adjustment section 152 and a fuel
supply line 153. The fuel storage section 151 stores the fuel F2, and is
configured of, for example, a tank or a cartridge. The fuel supply
adjustment section 152 adjusts the supply flow velocity and the supply
amount of the fuel F2. The fuel supply adjustment section 152 may be
configured of any component which is allowed to be driven by a signal
from the control section 130, and is not specifically limited, but the
fuel supply adjustment section 152 is preferably configured of, for
example, a valve driven by a motor or a piezoelectric device or an
electromagnetic pump. In addition, the fuel supply section 150 may
include a concentration adjustment section (not illustrated) adjusting
the supply concentration of the fuel F2. The concentration adjustment
section is allowed to be removed in the case where pure (99.9%) methanol
is used as the fuel F2, thereby the size of the fuel supply section 150
is allowed to be further reduced.

[0130] The fuel cell stack system 1 is manufacturable by, for example, the
following steps.

[0131] First, for example, an alloy including platinum (Pt) and ruthenium
(Ru) at a predetermined ratio as the catalyst and a dispersion solution
of a polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a registered
trademark)" manufactured by E. I. du Pont de Nemours and Company) are
mixed at a predetermined ratio to form the catalyst layer 11 of the fuel
electrode 10. The catalyst layer 11 is thermal compression bonded to the
diffusion layer 12 made of the above-described material. Moreover, the
current collector 13 made of the above-described material is thermal
compression bonded with a hot-melt adhesive or a resin sheet having
adhesion to form the fuel electrode 10.

[0132] Moreover, carbon-supported platinum as the catalyst and a
dispersion solution of a polyperfluoroalkyl sulfonic acid-based resin
("Nafion (a registered trademark)" manufactured by E. I. du Pont de
Nemours and Company) are mixed at a predetermined ratio to form the
catalyst layer 21 of the oxygen electrode 20. The catalyst layer 21 is
thermal compression bonded to the diffusion layer 22 made of the
above-described material. Moreover, the current collector 23 made of the
above-described material is thermal compression bonded with a hot-melt
adhesive or a resin sheet having adhesion to form the oxygen electrode
20.

[0133] Next, a resin sheet having adhesion is prepared, and a channel is
formed with the resin sheet to form the electrolytic solution channel 30
and the fuel channel 40, and the electrolytic solution channel 30 and the
fuel channel 40 are thermal compression bonded to both sides of the fuel
electrode 10.

[0134] Next, the external members 14 and 24 made of the above-described
material are formed, and in the external member 14, the fuel inlet 14A
and the fuel outlet 14B are arranged, and in the external member 24, the
electrolytic solution inlet 24A and the electrolytic solution outlet 24B
are arranged.

[0135] After that, the fuel electrode 10 and the oxygen electrode 20 are
arranged so as to face each other so that the electrolytic solution
channel 30 is arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 is arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 are contained in the external
members 14 and 24. Thereby, one fuel cell element illustrated in FIG. 2
is formed.

[0136] The plurality of fuel cell elements 111 are formed in the same
manner, and are stacked in a vertical direction, and the electrolytic
solution outlet 24B of one fuel cell element is connected to the
electrolytic solution inlet 24A of the next fuel cell element 111 through
the connection channel 24C, and the fuel outlet 14B of the one fuel cell
element is connected to the fuel inlet 14A of the next fuel cell element
111 through the connection channel 14C. Moreover, the separation room 160
is connected to a midpoint of each of the connection channels 14C and
24C. Thereby, the fuel cell stack 110 is formed.

[0137] The fuel cell stack 110 is mounted in a system including the
measurement section 120, the control section 130, the electrolytic
solution supply section 140 and the fuel supply section 150 all having
the above-described configurations, and the fuel inlet 14A of the first
fuel cell element 111 and the fuel outlet 14B of the last fuel cell
element 111 are connected to the fuel supply section 150 with the fuel
supply line 153 configured of, for example, a silicone tube. Moreover,
the electrolytic solution inlet 24A of the first fuel cell element 111
and the electrolytic solution outlet 24B of the last fuel cell element
111 are connected to the electrolytic solution supply section 140 with
the electrolytic solution supply line 143 configured of, for example, a
silicone tube. Thus, the fuel cell stack system 1 illustrated in FIG. 1
is completed.

[0138] In the fuel cell stack system 1, in each of the fuel cell elements
111, the fuel F2 is supplied to the fuel electrode 10 to produce protons
and electrons by a reaction. The protons move to the oxygen electrode 20
through the electrolytic solution F1 to react with electrons and oxygen,
thereby to produce water. Reactions occurring in the fuel electrode 10,
the oxygen electrode 20 and the whole fuel cell elements 111 are
represented by Chemical Formula 2. Thereby, a part of chemical energy of
methanol as the fuel is converted into electrical energy, and a current
is extracted from the fuel cell stack 110 to drive the external circuit
2.

[0139] (Chemical Formula 2)

[0140] Fuel electrode 10:
CH3OH+H2O→CO2+6e-+6H30

[0141] Oxygen electrode 20:
(3/2)O2+6e-+6H.sup.+→3H2O

[0142] Whole fuel cell elements 111:
CH3OH+(3/2)O2→CO2+2H2O

[0143] During operating the fuel cell stack 110, the operating voltage and
the operating current of the fuel cell stack 110 are measured by the
measurement section 120, and the above-described electrolytic solution
supply parameter and the above-described fuel supply parameter as
operating conditions of the fuel cell stack 110 are controlled by the
control section 130 according to measurement results. Measurement by the
measurement section 120 and parameter control by the control section 130
are frequently repeated so as to optimize the supply states of the
electrolytic solution F1 and the fuel F2 according to variations in
characteristics of the fuel cell stack 110.

[0144] In this case, the electrolytic solution channels 30 and the fuel
channels 40 of all of four fuel cell elements 111 are connected in series
to one another. The electrolytic solution F1 supplied from the
electrolytic solution supply section 140 enters the electrolytic solution
inlet 24A of the first fuel cell element 111A, and exits from the
electrolytic solution outlet 24B of the first fuel cell element 111A to
enter the electrolytic solution inlet 24A of the next fuel cell element
111B, and after the electrolytic solution F1 flows through all of the
fuel cell elements 111 in the same manner, the electrolytic solution F1
exits from the electrolytic solution outlet 24B of the last fuel cell
element 111 to return to the electrolytic solution supply section 140.
Moreover, the fuel F2 supplied from the fuel supply section 150 enters
the fuel inlet 14A of the first fuel cell element 111A, and exit from the
fuel outlet 14B of the first fuel cell element 111A to enter the fuel
inlet 14A of the next fuel cell element 111B, and after the fuel F2 flows
through all of the fuel cell elements 111 in the same manner, the fuel F2
exits from the fuel outlet 14B of the last fuel cell element 111 to
return to the fuel supply section 150. Therefore, influences such as
nonuniformity of the flow of the electrolytic solution F1 or the fuel F2
through each of the fuel cell elements 111, a change in pressure loss and
internal characteristics are reduced, and the fuel F2 or the electrolytic
solution F1 is uniformly supplied to each of the fuel cell elements 111.
Therefore, the stability of electric power generation is improved.

[0145] Thus, in the embodiment, the electrolytic solution channels 30 and
the fuel channels 40 of all of the plurality of fuel cell elements 111
are connected in series to one another, so the number of supply
auxiliaries such as pumps or valves is reduced, thereby the configuration
is allowed to be simplified. Moreover, influences such as nonuniformity
of the flow of the electrolytic solution F1 or the fuel F2 through each
of the fuel cell elements 111, a change in pressure loss and internal
characteristics are reduced, so that the fuel F2 or the electrolytic
solution F1 is allowed to be uniformly supplied to each of the fuel cell
elements 111. Therefore, the stability of electric power generation is
allowed to be improved, and the fuel cell stack system 1 is suitable for
a multifunctional high-performance electronic device consuming a large
amount of electric power.

[0146] In addition, in the above-described embodiment, the case where the
electrolytic solution channels 30 and the fuel channels 40 of all of the
plurality of fuel cell elements 111 are connected in series to one
another is described; however, as illustrated in FIG. 3, the fuel
channels 40 and the electrolytic solution channels 30 of some of the
plurality of fuel cell elements 111, for example, fuel cell elements
111A, 111B and 111C may be connected in series to one another, and the
fuel channel 40 and the electrolytic solution channel 30 of a fuel cell
element 111D may be connected in parallel with them. In this case, a fuel
F2S and an electrolytic solution F1S flow through the fuel cell elements
111A, 111B and 111C in series, and a fuel F2P and an electrolytic
solution F1P flows through the fuel cell element 111D in parallel with
the fuel F2S and the electrolytic solution F1S.

[0147] Moreover, as illustrated in FIGS. 4 and 5, one of the electrolytic
solution channels 30 and the fuel channels 40 of all of the plurality of
fuel cell elements 11 may be connected in series to one another. In
addition, FIG. 4 illustrates the case where the electrolytic solution
channels 30 of all of the plurality of fuel cell elements 111 are
connected in series to one another, and FIG. 5 illustrates the case where
the fuel channels 40 of all of the plurality of fuel cell elements 111
are connected in series to one another.

[0148] Further, as illustrated in FIG. 6, the fuel channels 40 of some of
the plurality of fuel cell elements 111, for example, the fuel cell
elements 111A, 111B and 111C may be connected in series to one another,
and the electrolytic solution channels 30 of all of the plurality of fuel
cell elements 111 may be connected in parallel to one another. In this
case, the fuel F2S flows through the fuel cell elements 111A, 111B and
111C in series, and the fuel F2P flows through the fuel cell element 111D
in parallel with the fuel F2S.

[0149] In addition, as illustrated in FIG. 7, the fuel channels 40 of all
of the plurality of fuel cell elements 111 may be connected in parallel
to one another, and the electrolytic solution channels 30 of some of the
plurality of fuel cell elements 111, for example, the fuel cell elements
111A, 111B and 111C may be connected in series to one another and the
electrolytic solution channel 30 of the fuel cell element 111D may be
connected in parallel to them. In this case, the electrolytic solution
F1S flows through the fuel cell elements 111A, 111B and 111C in series,
and the electrolytic solution F1P flows through the fuel cell element
111D in parallel with the electrolytic solution F1S.

[0150] In modification examples illustrated in FIGS. 3 to 7, the number of
parts where the electrolytic solution channels 30 and the fuel channels
40 are connected in series is preferably increased to a maximum possible
value. It is because the configuration is allowed to be further
simplified, and the stability of electric power generation is allowed to
be further improved.

[0151] (Second Embodiment)

[0152] FIG. 8 illustrates a schematic configuration of an electronic
device including a fuel cell system according to a second embodiment. The
electronic device has many commonalities with the electronic device
according to the above-described first embodiment, so like components
will be defined as such, and not be further described in detail.

[0153] The electronic device is, for example, a mobile device such as a
cellular phone or a PDA, or a notebook PC, and includes a fuel cell
system 1A and the external circuit (load) 2 which is driven by electrical
energy generated in the fuel cell system 1A.

[0154] The fuel cell system 1A has the same configuration as that of the
fuel cell stack system 1 of the first embodiment, except that, for
example, instead of the fuel cell stack 110, a fuel cell 110A configured
of one fuel cell element is included. That is, the fuel cell system 1A
includes the fuel cell 110A, the measurement section 120, the control
section 130, the electrolytic solution supply section 140 and the fuel
supply section 150.

[0155] The measurement section 120, the control section 130 and the fuel
supply section 150 are formed as in the case of the first embodiment. The
electrolytic solution supply section 140 includes the electrolytic
solution storage section 141, the electrolytic solution supply adjustment
section 142, the electrolytic solution supply line 143 and a separation
room 144, and allows the electrolytic solution F1 to circulate between
the fuel cell 110A and the electrolytic solution supply section 140. The
electrolytic solution storage section 141, the electrolytic solution
supply adjustment section 142 and the electrolytic solution supply line
143 are the same as those in the first embodiment. The separation room
144 is configured as in the case of the separation room 160 of the first
embodiment.

[0156]FIG. 9 illustrates a configuration of the fuel cell 110A
illustrated in FIG. 8. The fuel cell 110A includes the electrolytic
solution channel 30, which allows the electrolytic solution F1 to flow
therethrough, between the fuel electrode 10 and the oxygen electrode 20
as in the case of the fuel cell element 111 of the first embodiment. The
fuel channel 40 allowing the fuel F2 to flow therethrough is arranged on
the outside of the fuel electrode 10, that is, on a side opposite to a
side where the oxygen electrode 20 is arranged.

[0157] The fuel electrode 10 and the oxygen electrode 20 are configured as
in the case of the first embodiment.

[0158] FIG. 10 illustrates an outer appearance of the fuel channel 40. The
fuel channel 40 is a channel structure in which a plurality of (in FIG.
10, for example, 12) parallel channels 54 are arranged between a first
main channel 52 connected to a main inlet 52A for the fuel F2 and a
second main channel 53 connected to a main outlet 53A for the fuel F2 in
a substrate 51, and is bonded to the fuel electrode 10.

[0159] The substrate 51 has, for example, a thickness of 100 μm or
less, and is made of metal, glass, carbon, a resin, a porous material,
silicon (Si) or a silicon (Si)-based material, or ceramic. The shape of
the substrate 51 may be a plate or an adhesive or non-adhesive film.
Moreover, the substrate 51 may be configured of one plate or film, or a
plurality of plates or films bonded together. In the latter case, to
reliably bond the plurality of plates or films together, plates or films
made of a common material are preferably bonded together, but plates or
films made of different materials may be bonded together.

[0160] FIG. 11(A) illustrates a configuration of the fuel channel 40 when
viewed from a side where the first main channel 52, the second main
channel 53 and the parallel channels 54 are arranged, and FIG. 11(B)
illustrates a sectional configuration taken along a line XIB-XIB of FIG.
11(A). The first main channel 52 and the second main channel 53 are
formed as grooves parallel to each other, and the widths and the heights
(depths) of them are equal to each other. The widths and the heights of
the first main channel 52 and the second main channel 53 are not
specifically limited, but the heights and the widths are preferably
small, for example, 500 μm or less and 10 mm or less, respectively.
The first main channel 52 is connected to the fuel inlet 14A (not
illustrated in FIG. 10, refer to FIG. 9) through the main inlet 52A. The
second main channel 53 is connected to the fuel outlet 14B (not
illustrated in FIG. 10, refer to FIG. 9) through the main outlet 54A.

[0161] The inlet 54A and the outlet 54B of each of the plurality of
parallel channel 54 is connected to the first main channel 52 and the
second main channel 53 at a right angle, respectively, and the parallel
channels 54 are formed as grooves parallel to one another. Moreover, the
plurality of parallel channels 54 each have the same width and the same
height (depth) as those of the first main channel 52 and the second main
channel 53. That is, the sectional areas of the first main channel 52 and
the second main channel 53 are equal to the sectional areas of the
parallel channels 54.

[0162] Moreover, the plurality of parallel channels 54 each have a region
of which the sectional area is reduced by arranging a rib 55 at each of
the inlet 54A and the outlet 54B. Thereby, in the fuel channel 40, the
fuel F2 is allowed to uniformly flow through the parallel channels 54.

[0163] The rib 55 has a function as a barrier to the flow of the fuel F2.
That is, when the rib 55 is arranged, even if the substrate 51 is thinner
and the sectional areas of the first main channel 52 and the second main
channel 53 are equal to the sectional areas of the parallel channels 54,
the resistance of the first main channel 52 and the second main channel
53 to the flow is reduced, and on the other hand, the uniformity of the
flow through the parallel channels 54 is allowed to be improved.
Therefore, the thickness and the size of the fuel cell 110A or a fuel
cell stack formed by stacking the fuel cells 110A are allowed to be
remarkably reduced.

[0164] For example, as illustrated in FIG. 11(C), the rib 55 blocks a
lower part of the parallel channel 54. The height H1 of the rib 55 is
dependent on the height H0 of the parallel channel 54, and is, for
example, within a range of 1% to 99.9% of the height H0 of the parallel
channel 54. As the height H1 of the rib 55 is increased, the resistance
of the first main channel 52 and the second main channel 53 to the flow
is reduced, thereby to allow the fuel F2 to easily flow through the first
main channel 52 and the second main channel 53, and the uniformity of the
flow of the fuel F2 through the parallel channels 54 is allowed to be
improved. The thickness T1 of the rib 55 depends on application, and is,
for example, within a range of approximately 0.5 mm to 1 mm.

[0165] Such a fuel channel 40 is connected to the fuel supply section 150
(not illustrated in FIG. 9, refer to FIG. 8) through the fuel inlet 14A
and the fuel outlet 14B arranged in the external member 14, and the fuel
F2 is supplied from the fuel supply section 150 to the fuel channel 40.

[0166] FIG. 12 illustrates an outer appearance of the electrolytic
solution channel 30. Moreover, FIG. 13(A) illustrates a configuration of
the electrolytic solution channel 30 when viewed from a side where the
first main channel 52, the second main channel 53 and the parallel
channels 54 are arranged, and FIG. 13(B) illustrates a sectional
configuration taken along a line VIB-VIB of FIG. 13(A), and FIG. 13(C)
illustrates a sectional configuration of the rib 55 in one parallel
channel 54. As in the case of the fuel channel 40, the electrolytic
solution channel 30 is a channel structure in which a plurality of (in
FIG. 10, for example, 12) parallel channels 54 are arranged between the
first main channel 52 connected to the main inlet 52A for the
electrolytic solution F1 and the second main channel 53 connected to the
main outlet 53A for the electrolytic solution F1 in the substrate 51.
Therefore, like components will be described using like numerals.

[0167] The substrate 51 is configured as in the case of the fuel channel
40.

[0168] The first main channel 52, the second main channel 53 and the
parallel channels 54 allow the electrolytic solution F1 to come into
contact with both of the fuel electrode 10 and the oxygen electrode 20
(refer to FIG. 9), so they are configured as in the case of the fuel
channel 40, except that they are formed so as to penetrate through the
substrate 51. Moreover, as in the case of the fuel channel 40, the
sectional areas of the first main channel 52 and the second main channel
53 are equal to the sectional areas of the parallel channels 54.

[0169] As in the case of the fuel channel 40, the plurality of parallel
channels 54 each have a region of which the sectional area is reduced by
arranging the rib 55 at each of the inlet 54A and the outlet 54B. As in
the case of the fuel channel 40, the height H1 of the rib 55 is dependent
on the height H0 of the parallel channel 54, and is, for example, within
a range of 1% to 99.9% of the height H0 of the parallel channel 54. As
the height H1 of the rib 55 is increased, the resistance of the first
main channel 52 and the second main channel 53 to the flow is reduced,
thereby to allow the fuel F1 to easily flow through the first main
channel 52 and the second main channel 53, and the uniformity of the flow
of the fuel F1 through the parallel channels 54 is allowed to be
improved.

[0170] Such an electrolytic solution channel 30 is connected to the
electrolytic solution supply section 140 (not illustrated in FIG. 9,
refer to FIG. 8) through the electrolytic solution inlet 24A and the
electrolytic solution outlet 24B arranged in the external member 24, and
the electrolytic solution F1 is supplied from the electrolytic solution
supply section 140 to the electrolytic solution channel 30.

[0171] The fuel cell system 1A is manufacturable by, for example, the
following steps. [0119] First, as in the case of the first embodiment,
the fuel electrode 10 and the oxygen electrode 20 are formed.

[0172] Next, the substrate 51 made of the above-described material is
prepared, and the first main channel 52, the second main channel 53 and
the parallel channels 54 illustrated in FIGS. 10 and 11 are formed in the
substrate 51, and the ribs 55 are formed at the inlets 54A and the outlet
54B of the parallel channels 54 so as to form the fuel channel 40.
Moreover, the electrolytic solution channel 30 illustrated in FIGS. 12
and 13 are formed in the same manner, and the fuel channel 40 and the
electrolytic solution channel 30 are thermal compression bonded to both
sides of the fuel electrode 10.

[0173] Next, the external members 14 and 24 made of the above-described
material are formed, and the fuel inlet 14A and the fuel outlet 14B
configured of, for example, joints made of a resin are arranged in the
external member 14, and the electrolytic solution inlet 24A and the
electrolytic solution outlet 24B configured of, for example, joints made
of a resin are arranged in the external member 24.

[0174] After that, the fuel electrode 10 and the oxygen electrode 20 are
arranged so as to face each other so that the electrolytic solution
channel 30 is arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 is arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 are contained in the external
members 14 and 24. Thereby, the fuel cell 110 illustrated in FIG. 9 is
completed.

[0175] The fuel cell 110 is mounted in a system including the measurement
section 120, the control section 130, the electrolytic solution supply
section 140 and the fuel supply section 150 all having the
above-described configurations, and the fuel inlet 14A and the fuel
outlet 14B are connected to the fuel supply section 150 through the fuel
supply line 153 configured of, for example, a silicone tube, and the
electrolytic solution inlet 24A and the electrolytic solution outlet 24B
are connected to the electrolytic solution supply section 140 through the
electrolytic solution supply line 143 configured of, for example, a
silicone tube. Thus, the fuel cell system 1A illustrated in FIG. 8 is
completed.

[0176] In the fuel cell system 1A, as in the case of the above-described
first embodiment, battery reactions by Chemical Formula 2 occur. At this
time, in the fuel channel 40, as illustrated in FIGS. 11(A) and 11(B),
the fuel F2 enters from the main inlet 52A into the first main channel
52, and then enters from the first main channel 52 into the inlets 54A of
the parallel channels 54 to flow through the parallel channels 54, and
then the fuel F2 enters from the outlets 54B into the second main channel
53 to exit from the main outlet 53A. Moreover, in the electrolytic
solution channel 30, as illustrated in FIGS. 13(A) and 13(B), the
electrolytic solution F1 enters from the main inlet 52A into the first
main channel 52, and then enters from the first main channel 52 into the
inlets 54A of the parallel channels 54 to flow through the parallel
channels 54, and then the electrolytic solution F2 enters from the
outlets 54B into the second main channel 53 to exit the main outlet 53A.
In this case, the region of which the sectional area is reduced by
forming the rib 55 is arranged at each of the inlets 54A and the outlets
54B of the parallel channels 54, so the rib 55 becomes a barrier to the
flow of the fuel F2 or the electrolytic solution F1, and the resistance
of the first main channel 52 and the second main channel 53 to the flow
is reduced, thereby to allow the fuel F2 or the electrolytic solution F2
to easily flow through the first main channel 52 and the second main
channel 53, and the uniformity of the flow of the fuel F2 or the
electrolytic solution F1 through the parallel channels 54 is improved.

[0177] On the other hand, in related art, to maintain uniformity of the
flow through the parallel channels, it is necessary to increase the
thickness of a substrate to 1 mm or over. In the invention, as the rib 55
is arranged, the thickness of the substrate 51 is 100 μm or less which
is extremely thin, and even if the sectional areas of the first main
channel 52 and the second main channel 54 are equal to the sectional
areas of the parallel channels 54, the resistance of the first main
channel 52 and the second main channel 53 to the flow is reduced, and on
the other hand, the uniformity of the flow through the parallel channels
54 is improved.

[0178] Thus, in the embodiment, the region of which the sectional area is
reduced by the rib 55 is arranged at each of the inlets 54A and the
outlets 54B of two or more parallel channels 54, so the fuel F2 or the
electrolytic solution F1 is allowed to uniformly flow through the
parallel channels 54. Therefore, the electric power generation
characteristics of the fuel cell 110A are allowed to be improved, and the
fuel cell system 1A is suitable for a multifunctional high-performance
electronic device consuming a large amount of electric power.

[0179] (Third Embodiment)

[0180]FIG. 14 illustrates a configuration of a fuel cell 110B of a fuel
cell system 1A according to a third embodiment. The fuel cell system 1A
has the same configuration as that of the above-described second
embodiment, except that in the fuel cell 110B, a functional layer 51 and
a functional layer 52 are arranged on the fuel electrode 10 and the
oxygen electrode 20, respectively. Therefore, like components will be
described using like numerals.

[0181] The catalyst layers 11 and 21, the diffusion layers 12 and 22, the
current collectors 13 and 23 and the external members 14 and 24 of the
fuel electrode 10 and the oxygen electrode 20 are configured as in the
case of the first embodiment.

[0182] The functional layer (a contact inhibition layer) 51 inhibiting
direct contact between the catalyst layer 11 and the electrolytic
solution F1 is arranged on the catalyst layer 11 of the fuel electrode
10. Moreover, the functional layer (contact inhibition layer) 52
inhibiting direct contact between the catalyst layer 21 and the
electrolytic solution F1 is arranged on the catalyst layer 21 of the
oxygen electrode 20. Thereby, in the fuel cell 110, deterioration of the
fuel electrode 10 or the oxygen electrode 20 is preventable.

[0183] The functional layer 51 arranged on the fuel electrode 10 is an
anti-deterioration layer preventing deterioration such as a crack or a
hole of the fuel electrode 10 caused by direct contact between the
catalyst layer 11 and the electrolytic solution F1 while maintaining an
ion path between the electrolytic solution F1 and the catalyst layer 11.
Moreover, the functional layer 51 also has a function of reducing fuel
crossover (a crossover inhibition layer) and a function of preventing
carbon dioxide (CO2) as bubbles generated by a reaction in the fuel
electrode 10 from being released into the electrolytic solution F1 (a
bubble release direction control layer). The generated carbon dioxide as
bubbles is released into both of the electrolytic solution F1 in the
electrolytic solution channel 30 and the fuel F2 in the fuel channel 40.
Carbon dioxide released into the fuel F2 is not an issue, but carbon
dioxide released into the electrolytic solution F1 may cause a fatal
issue. It is because a proton path is blocked by release of carbon
dioxide bubbles to cause a change in proton conductivity and instability
in characteristics in an area where bubbles are present. When the
functional layer 51 is arranged, the direction where carbon dioxide
bubbles are released is controllable, thereby to allow carbon dioxide
released into the electrolytic solution F1 to be remarkably reduced.

[0184] The functional layer 52 arranged in the oxygen electrode 20 is an
anti-deterioration layer preventing deterioration such as a crack or a
hole of the oxygen electrode 20 caused by direct contact between the
catalyst layer 21 and the electrolytic solution F1 while maintaining an
ion path between the electrolytic solution F1 and the catalyst layer 21
and preventing leakage of the electrolytic solution F1. Moreover, the
functional layer 52 also has a function of preventing overvoltage
generated in the oxygen electrode 20 due to fuel crossover (an
overvoltage prevention layer) and a function of preventing flooding of
the oxygen electrode 20 (a flooding prevention layer). The oxygen
electrode 20 is consistently in contact with the electrolytic solution
F1, and is in a state in which flooding consistently occurs irrespective
of whether electric power is generated or not, but when the functional
layer 52 is arranged, the flooding state of the oxygen electrode 20 is
allowed to be relieved.

[0185] The functional layers 51 and 52 are made of, for example, a porous
material. An ion path between the electrolytic solution F1 and the
catalyst layers 11 and 21 is allowed to be secured by pores contained in
the porous material. As the porous material, specifically metal, carbon,
a resin such as polyimide or ceramic is cited, and a blend layer made of
a plurality of materials selected from them may be used. The resin may be
a water-repellent resin or a hydrophilic resin. The thicknesses of the
functional layers 51 and 52 are, for example, approximately 10 μm to
15 μm, and are preferably as thin as possible.

[0186] The pores of the functional layers 51 and 52 preferably have, for
example, a diameter ranging from nanometers to micrometers, but they are
not specifically limited. However, the diameters of the pores in the
functional layers 51 and 52 are preferably smaller than the diameters of
pores contained in the fuel electrode 10 or the oxygen electrode 20. It
is because it is necessary that carbon dioxide generated as bubbles
selectively passes through the fuel electrode 10 to be released toward
the fuel F2. Moreover, needless to say, a porous material with a thin
pore diameter has a higher function of preventing methanol crossover than
a porous material with a large pore diameter.

[0187] The functional layers 51 and 52 may be made of an ion conductor
such as a proton conductor. Examples of the proton conductor include a
polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a registered
trademark)" manufactured by E. I. du Pont de Nemours and Company),
polystyrene sulfonate, a fullerene-based conductor, a solid acid and
other resin having proton conductivity.

[0188] For example, the electrolytic solution channel 30 and the fuel
channel 40 are configured as in the case of the first embodiment. The
electrolytic solution channel 30 is connected to the electrolytic
solution supply section 140 (not illustrated in FIG. 14, refer to FIG. 8)
through the electrolytic solution inlet 24A and the electrolytic solution
outlet 24B arranged in the external member 24, and the electrolytic
solution F1 is supplied from the electrolytic solution supply section 140
to the electrolytic solution channel 30. The fuel channel 40 is connected
to the fuel supply section 150 (not illustrated in FIG. 14, refer to FIG.
8) through the fuel inlet 14A and the fuel outlet 14B arranged in the
external member 14, and the fuel F2 is supplied from the fuel supply
section 150 to the fuel channel 40.

[0189] The fuel cell system 1A is manufacturable by, for example, the
following steps.

[0190] First, as in the case of the first embodiment, the catalyst layer
11 of the fuel electrode 10 is formed. The catalyst layer 11 is thermal
compression bonded to the diffusion layer 12 made of the above-described
material. Moreover, the functional layer 51 made of the above-described
material is formed on a surface where the diffusion layer 12 is not
thermal compression bonded of the catalyst layer 11.

[0191] As a method of forming the functional layer 51, for example, a
bar-coating method is preferable. It is because the functional layer 51
is applicable with a uniform thickness. In addition, the method of
forming the functional layer 51 is not limited to the bar coating method,
and any other coating method such as a gravure coating method, a roll
coating method, a spin coating method, a dip coating method, a doctor bar
coating method, a wire bar coating method, a blade coating method, a
curtain coating method, a spray coating method may be used. Moreover,
another member may coated with a coating liquid including the material of
the functional layer 51, and the coating liquid may be dried to form a
porous film, and then the porous film may be transferred to the catalyst
layer 11. Moreover, the functional layer 51 made of the above-described
material may be thermal compression bonded to the catalyst layer 11.

[0192] Moreover, the current collector 13 made of the above-described
material is thermal compression bonded with a hot-melt adhesive or a
resin sheet having adhesion to form the fuel electrode 10.

[0193] Further, as in the case of the first embodiment, the catalyst layer
21 of the oxygen electrode 20 is formed. The catalyst layer 21 is thermal
compression bonded to the diffusion layer 22 made of the above-described
material. Moreover, the functional layer 52 made of the above-described
material is formed on a surface where the diffusion layer 22 is heat
compression bonded of the catalyst layer 21. A method of forming the
functional layer 52 is the same as the above-described method of forming
the functional layer 51. Further, the current collector 23 made of the
above-described material is thermal compression bonded with a hot-melt
adhesive or a resin sheet having adhesion to form the oxygen electrode
20.

[0194] Next, a resin sheet having adhesion is prepared, and a channel is
formed with the resin sheet to form the electrolytic solution channel 30
and the fuel channel 40, and the electrolytic solution channel 30 and the
fuel channel 40 are thermal compression bonded to both sides of the fuel
electrode 30.

[0195] Next, the external members 14 and 24 made of the above-described
material are formed, and the fuel inlet 14A and the fuel outlet 14B, and
the electrolytic solution inlet 24A and the electrolytic solution outlet
24B are arranged in the external member 14 and the external member 24,
respectively.

[0196] After that, the fuel electrode 10 and the oxygen electrode 20 are
arranged so as to face each other so that the electrolytic solution
channel 30 is arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 is arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 are contained in the external
members 14 and 24. Thereby, the fuel cell 110B illustrated in FIG. 14 is
completed.

[0197] The fuel cell 110B is mounted in a system including the measurement
section 120, the control section 130, the electrolytic solution supply
section 140 and the fuel supply section 150 all having the
above-described configurations, and the fuel inlet 14A and the fuel
outlet 14B are connected to the fuel supply section 150 through the fuel
supply line 153 made of, for example, a silicone tube, and the
electrolytic solution inlet 24A and the electrolytic solution outlet 24B
are connected to the electrolytic solution supply section 140 through the
electrolytic solution supply line 143 made of, for example, a silicone
tube. Thus, the fuel cell system 1A illustrated in FIG. 8 is completed.

[0198] In the fuel cell system 1A, as in the case of the above-described
first embodiment, battery reactions by Chemical Formula 2 occur. In this
case, the functional layers 51 and 52 preventing direct contact between
the catalyst layers 11 and 21 and the electrolytic solution F2 are
arranged on the catalyst layers 11 and 21, so deterioration such as a
crack or a hole of the fuel electrode 10 or the oxygen electrode 20 is
prevented. Therefore, fuel crossover due to deterioration of the fuel
electrode 10 or leakage of the electrolytic solution F2 due to
deterioration of the oxygen electrode 20 is reduced, and stable
characteristics are maintained, and long-time electric power generation
is allowed.

[0199] Moreover, the fuel electrode 10 is arranged between the
electrolytic solution channel 30 and the fuel channel 40, so almost all
of the fuel reacts when flowing through the fuel electrode 10. Even if
the fuel F2 passes through the fuel electrode 10 without reaction, fuel
crossover is remarkably prevented by the functional layer 51 arranged on
the catalyst layer 11, and a possibility that the fuel F2 reaches the
oxygen electrode 20 is extremely low. Therefore, a high-concentration
fuel is applicable, and high energy density characteristics as an
intrinsic advantage of the fuel cell are utilized.

[0200] Further, carbon dioxide generated in the fuel electrode 10 is
prevented from being released into the electrolytic solution F2 by the
functional layer 51 arranged on the catalyst layer 11, and the carbon
dioxide is released into the fuel F2 to flow with the fuel F2, thereby to
be removed. Therefore, conductivity is prevented from being lost due to
carbon dioxide bubbles mixed into the electrolytic solution F1. In
addition, water generated in the oxygen electrode 20 flows with the
electrolytic solution F1 to be removed.

[0201] Thus, in the embodiment, the functional layers 51 and 52 preventing
direct contact between the catalyst layers 11 and 21 and the electrolytic
solution F2 are arranged on the catalyst layers 11 and 21, so
deterioration such as a crack or a hole of the fuel electrode 10 or the
oxygen electrode 20 is preventable. Therefore, a decline in
characteristics of the fuel cell 110 is prevented, and long-time electric
power generation is allowed, and the embodiment is suitable for a
multifunctional high-performance electronic device consuming a large
amount of electric power.

[0202] In addition, in the above-described embodiment, the case where the
functional layers 51 and 52 are arranged in the fuel electrode 10 and the
oxygen electrode 20, respectively is described; however, for example, as
illustrated in FIG. 15, the functional layer 51 may be arranged on the
catalyst layer 11 of the fuel electrode 10, and the functional layer 52
of the oxygen electrode 20 may be removed. Moreover, as illustrated in
FIG. 16, the functional layer 52 may be arranged on the catalyst layer 21
of the oxygen electrode 20, and the functional layer 41 of the fuel
electrode 10 may be removed.

[0203] (Fourth Embodiment)

[0204]FIG. 17 illustrates a configuration of a fuel cell 110B according
to a fourth embodiment. In the fuel cell 110B, a gas-liquid separation
film 60 is arranged between the fuel channel 40 and the fuel electrode
10, and the fuel cell 110B is configured as in the case of the
above-described third embodiment, except for this. Therefore, like
components will be described using like numerals.

[0205] The gas-liquid separation film 60 may be configured of, for
example, a film not allowing alcohol in a liquid form to pass
therethrough such as polytetrafluoroethylene (PTFE), polyvinylidene
fluoride (PVDF) or polypropylene (PP).

[0206] The fuel cell 110B and the fuel cell system 1A using the fuel cell
110B are manufacturable as in the case of the above-described
embodiments, except that the gas-liquid separation film 60 is arranged
between the fuel channel 40 and the fuel electrode 10.

[0207] In the fuel cell system, as in the case of the above-described
embodiments, a current is extracted from the fuel cell 110B to drive the
external circuit 2. In this case, as the gas-liquid separation film 60 is
arranged between the fuel channel 40 and the fuel electrode 10, when pure
methanol as the fuel flows through the fuel channel 40 in a liquid form,
pure methanol volatilizes spontaneously, and passes through the
gas-liquid separation film 60 in the form of a gas G from a surface in
contact with the gas-liquid separation film 60 to be supplied to the fuel
electrode 10. Therefore, the fuel is efficiently supplied to the fuel
electrode 10, and a reaction stably occurs. Moreover, the fuel is
supplied to the fuel electrode 10 in a gas form, so electrode reaction
activity is improved, and crossover is less prone to occur, and high
performance is obtained in an electronic device including a high-load
external circuit 2.

[0208] In addition, even if methanol in a gas form having passed through
the fuel electrode 10 is present, as in the case of the above-described
embodiments, fuel crossover is remarkably prevented by the functional
layer 51 on the catalyst layer 11, thereby there is an extremely low
possibility that methanol reaches the oxygen electrode 20.

[0209] Thus, in the embodiment, as the gas-liquid separation film 60 is
arranged between the fuel channel 40 and the fuel electrode 10, pure
(99.9%) methanol is applicable as the fuel F2, and high energy density
characteristics as an advantage of the fuel cell is allowed to be further
utilized. Moreover, reaction stability or electrode reaction activity is
allowed to be improved, and crossover is preventable. Therefore, also in
an electronic device having the high-load external circuit 2, high
performance is obtainable. Further, in the fuel supply section 150, a
concentration adjustment section adjusting the supply concentration of
the fuel F2 is allowed to be removed, so the size of the fuel supply
section 150 is allowed to be further reduced.

[0210] (Fifth Embodiment)

[0211] FIGS. 18 and 19 illustrate a configuration of a channel structure
according to a fifth embodiment. A channel structure 200 is used as, for
example, a micro TAS, and includes a channel 220 for fluid formed in a
base 210 and a fluid connector 230 connected to the channel 220.

[0212] The base 210 is formed by cutting a thin plate made of glass,
silicon (Si) or the like or bonding the thin plates together or bonding
flexible films such as plastic films together. More specifically, as
illustrated in FIG. 20, the base 210 is formed by cutting a thin plate
210A made of metal, plastic or the like to form the channel 220, and
bonding another thin plate or flexible film 210B to the thin plate 210A,
or as illustrated in FIG. 21, the base 210 is formed by bonding a thin
plate or flexible film 210C in which an incision corresponding to the
shape of the channel 220 is arranged to another thin plates or flexible
films 210B and 210D. Therefore, the sectional shape of the channel 220 is
rectangular. In addition, as long as two ends 221 as an inlet and an
outlet for fluid are included, the planar shape of the channel 220 is not
specifically limited. Moreover, the end 221 on the inlet side is not
necessarily arranged only at one point, and the ends 221 on the inlet
side may be arranged at two or more points, and different fluids may be
introduced into the channel 220 from the ends 221, respectively.

[0213] The fluid connector 230 introduces and guides the fluid into the
channel 220 from an external system (not illustrated), and has a
different sectional shape from the sectional shape of the channel 220.
For example, the sectional shape of the channel 220 is rectangular as
described above, but the fluid connector 230 is, for example, a
cylindrical tube made of polyolefin.

[0214] The fluid connector 230 is connected to a main surface of the base
210 in a direction parallel to the channel 220. Thereby, in the channel
structure 200, a space for connection of the fluid connector 230 is
allowed to be reduced.

[0215] More specifically, the ends 221 of the channel 220 are formed in
projections 211 projected from a side surface of the base 210 in a
direction parallel to the main surface of the base 210, and the fluid
connector 230 is connected to the projections 211, and a heat-shrinkable
tube 240 is arranged on a connection part between the projection 211 and
the fluid connector 230. The heat-shrinkable tube 240 allows connection
between the channel 220 and the fluid connector 230 with different
sectional shapes, and is made of, for example, polyolefin. Moreover, when
the heat-shrinkable tube 240 is arranged, even if the base 210 is thinner
than the tube diameter (outside diameter) of the fluid connector 230, the
fluid connector 230 is connectable in a direction parallel to the main
surface of the base 210, and the base 210 is allowed to be extremely
thin. In addition, the projections 211 may be projected in parallel with
the main surface of the base 210, and are not necessarily projected in a
direction perpendicular to the side surface of the base 210.

[0216] The channel structure 200 is manufacturable by, for example, the
following steps.

[0217] First, as illustrated in FIG. 2 the thin plate 210A is cut to form
the channel 220, and the channel 220 is bonded to another thin plate
210B, or as illustrated in FIG. 21, the thin plate or flexible film 210B
in which an incision corresponding to the shape of the channel 220 is
arranged is bonded to another thin plates or flexible films 210B and
210D, thereby the base 210 including the channel 220 inside thereof is
formed. At this time, the projections 211 projected from the side surface
of the base 210 in a direction parallel to the main surface of the base
210 are arranged, and the ends 221 of the channel 220 are formed in the
projections 211.

[0218] Next, the heat-shrinkable tube 240 made of the above-described
material is prepared, and the projection 211 is put into an end of the
heat-shrinkable tube 240. Next, a part put on the projection 211 of the
heat-shrinkable tube 240 is adhered to the projection 211. For this
adhesion, for example, an adhesive may be used, or a surface of the
projection 211 and the inside of the heat-shrinkable tube 240 may be made
of a material having thermal adhesion.

[0219] After that, the fluid connector 230 made of the above-described
material is prepared, and the fluid connector 230 is put into the other
end of the heat-shrinkable tube 240, and a part put on the fluid
connector 230 of the heat-shrinkable tube 240 is adhered to the fluid
connector 230. For this adhesion, for example, an adhesive may be used,
or a surface of the fluid connector 230 and the inside of the
heat-shrinkable tube 240 may be made of a material having thermal
adhesion. In addition, in the case where the base 210 and the projections
211 are made of a deformable material, the fluid connector 230 may be put
into the ends 221 of the channel 220 in the projection 211. Thus, the
channel structure 200 illustrated in FIGS. 18 and 19 is completed.

[0220] In the channel structure 200, the fluid is introduced into the
channel 220 from the external system (not illustrated) through the fluid
connector 230 and the end 221 on the inlet side, and the mixture,
reaction, separation, detection or the like is performed on the fluid in
the channel 220, and then the fluid is emitted from the end 221 on the
outlet side through the fluid connector 230.

[0221] Thus, in the embodiment, the fluid connector 230 is connected to
the channel 220 in a direction parallel to the main surface of the base
210, so a space for connection of the fluid connector 230 is allowed to
be reduced. Therefore, the bases 210 to which the fluid connector 230 is
connected are allowed to be stacked in parallel, and integration is
allowed to be improved.

[0222] (Modification Example)

[0223] FIG. 22 illustrates the end 221 of the channel 220 according to a
modification example. In the modification example, in the case where
unlike the above-described embodiment, it is difficult to form the
projection 211 on the side surface of the base 210, and the ends 221 of
the channel 220 are formed parallel to the side surface of the base 210,
the fluid connector 230 is connected to the channel 220 with an auxiliary
component 250 in between, and the heat-shrinkable tube 240 is arranged
between auxiliary component 250 and the fluid connector 230. Also in such
a case, the fluid connector 230 is connectable to the channel 220 in a
direction parallel to the main surface of the base 210, and a space for
connection of the fluid connector 230 is allowed to be reduced, and
integration is allowed to be improved.

[0224] In the auxiliary component 250, a curved channel 251 curved at
90° from the end 221 of the channel 220 is formed, and as
illustrated in FIG. 23, the auxiliary component 250 is formed by bonding
three films 252A, 252B and 252C made of plastic together. In the film
252A, a connection hole 252A1 connected to the end 221 of the channel 220
is arranged. In the film 252B, a cutout part 252B with a shape
corresponding to the curved channel 251 is arranged. A thermosetting
adhesive (not illustrated) is arranged on both sides of the film 252B,
thereby the films 252A to 252C are allowed to be bonded together by
stacking them and applying heat to them. In addition, an adhesive may be
arranged on a back surface of the film 252A so as to be used for adhesion
to the base 210 which is desired to be connected.

[0225] (Application Example 1)

[0226] Other application examples of the channel structure 200 according
to the above-described fifth embodiment will be described below. FIG. 24
illustrates an example in which the channel structure 200 is applied to a
fuel channel of a fuel cell. The fuel cell is a so-called polymer
electrolyte fuel cell (PEFC), and includes an electrolyte film 263
between a fuel electrode (anode) 261 and an oxygen electrode (cathode)
262. The channel structure 200 according to the above-described
embodiment is arranged on the outside of the fuel electrode 261, and
methanol as a fuel is supplied to the fuel electrode 261 through the
channel 220 of the channel structure 200. In addition, in the application
example, the fuel electrode 261 is arranged instead of the thin plate or
flexible film 210B illustrated in FIGS. 20 and 21, and the fuel in the
channel 220 is allowed to come into contact with the fuel electrode 261.
An external member 264 configured of a titanium (Ti) plate or the like is
arranged on the outside of the oxygen electrode 262.

[0227] The fuel electrode 261 and the oxygen electrode 262 are formed by
forming a catalyst layer including platinum (Pt), ruthenium (Ru) or the
like on a surface of a carbon cloth or the like, and then arranging a
current collector configured of a titanium (Ti) mesh on a back surface of
the carbon cloth or the like. The electrolyte film 263 is configured of,
for example, a polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a
registered trademark)" manufactured by E. I. du Pont de Nemours and
Company) or another resin film having proton conductivity. The fuel
electrode 261, the oxygen electrode 262 and the electrolyte film 263 are
fixed by a gasket (not illustrated).

[0228] The fuel cell is manufacturable by, for example, the following
steps. First, the electrolyte film 263 made of the above-described
material is sandwiched between the fuel electrode 261 and the oxygen
electrode 262 which are made of the above-described materials, and the
fuel electrode 261 and the oxygen electrode 262 is thermal compression
bonded to the electrolyte film 263. The channel structure 200 of the
above-described embodiment is arranged on the outside of the fuel
electrode 261, and the external member 263 made of the above-described
material is arranged on the outside of the oxygen electrode 262. Thus,
the fuel cell illustrated in FIG. 24 is completed.

[0229] In the fuel cell, as in the case of the above-described first
embodiment, battery reactions by Chemical Formula 2 occur. At this time,
methanol as the fuel is introduced into the channel 220 from an external
fuel tank (not illustrated) through the fluid connector 230 and the end
221 on the inlet side to come into contact with the catalyst layer of the
fuel electrode 261 in the channel 220, thereby a battery reaction by a
first formula in Chemical Formula 2 occurs, and then methanol is emitted
from the end 221 on the outlet side through the fluid connector 230.

[0230] According to Application Example 1, the channel structure 200
according to the above-described embodiment is arranged as a fuel supply
path, so a space for connection of the fluid connector 230 is allowed to
be reduced, and the thickness of the fuel channel is allowed to be
reduced. Therefore, the fuel cells with a smaller thickness are allowed
to be stacked in parallel, and integration is allowed to be improved.

[0231] (Application Example 2)

[0232]FIG. 25 illustrates a configuration example of another fuel cell to
which the channel structure 200 of the above-described fifth embodiment
is applied. In the fuel cell, for example, instead of the electrolyte
film 263, the channel structure 200 of the above-described embodiment is
arranged, and an electrolytic solution (for example, a sulfuric acid) as
a liquid electrolyte is supplied between the fuel electrode 261 and the
oxygen electrode 262. Except for this, the fuel cell of the application
example is configured as in the case of the above-descried Application
Example 1. In addition, the fluid connector 230 of the channel structure
200 as a fuel channel and the fluid connector 230 of the channel
structure 200 as an electrolytic solution channel are not necessarily
connected to different positions as illustrated in FIG. 25, and may be
stacked so as to be connected to a common position.

[0233] The fuel cell is manufacurable as in the case of the
above-described Application Example 1, except that instead of the
electrolyte film 263, the channel structure 200 of the above-described
embodiment is arranged.

[0234] In the fuel cell, battery reactions by Chemical Formula 2 occur as
in the case of the above-described Application Example 1. At this time,
the fuel is supplied to the fuel electrode 261 through the channel 220 of
the channel structure 200 as in the case of the above-described
application example. Moreover, the electrolytic solution is introduced
into the channel 220 from an external electrolytic solution tank (not
illustrated) through the fluid connector 230 and the end 221 on the inlet
side, and is emitted with carbon dioxide or the like generated in the
reaction from the end 221 on the outlet side through the fluid connector
230. In addition, the fuel having passed through the fuel electrode 261
is also removed with the electrolytic solution before reaching the oxygen
electrode 262, thereby crossover is prevented.

[0235] Thus, according to Application Example 2, in addition to the fuel
supply path, the channel structure 200 according to the above-described
embodiment is also arranged as an electrolytic solution supply path, so a
space for connection of the fluid connector 230 is allowed to be reduced,
and a gap between the fuel electrode 261 and the oxygen electrode 262 is
allowed to be reduced. Therefore, the fuel cells with a smaller thickness
are allowed to be stacked in parallel, and integration is allowed to be
improved.

EXAMPLES

[0236] Moreover, specific examples will be described below.

Example 1

[0237] In the following Example 1, the fuel cell stack 110 configured of
two fuel cell elements 111A and 111B as illustrated in FIG. 2 was formed,
and its characteristics were evaluated. Therefore, referring to FIGS. 1
and 2, like components will be described using like numerals.

[0238] The fuel cell stack 110 having the same configuration illustrated
in FIG. 2 was formed. First, an alloy including platinum (Pt) and
ruthenium (Ru) at a predetermined ratio as a catalyst and a dispersion
solution of a polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a
registered trademark)" manufactured by E. I. du Pont de Nemours and
Company) were mixed at a predetermined ratio to form the catalyst layer
11 of the fuel electrode 10. The catalyst layer 11 was thermal
compression bonded to the diffusion layer 12 made of the above-described
material (HT-2500 manufactured by E-TEK Inc.) for 10 minutes under the
conditions where the temperature was 150° C. and the pressure was
249 kPa. Further, the current collector 13 made of the above-described
material was thermal compression bonded with a hot-melt adhesive or a
resin sheet having adhesion to form the fuel electrode 10.

[0239] Moreover, carbon-supported platinum (Pt) as a catalyst and a
dispersion solution of a polyperfluoroalkyl sulfonic acid-based resin
("Nafion (a registered trademark)" manufactured by E. I. du Pont de
Nemours and Company) were mixed at a predetermined rate to form the
catalyst layer 21 of the oxygen electrode 20. The catalyst layer 21 was
thermal compression bonded to the diffusion layer 22 made of the
above-described material (HT-2500 manufactured by E-TEK Inc.) as in the
case of the catalyst layer 11 of the fuel electrode 10. Further, the
current collector 23 made of the above-described material was thermal
compression bonded as in the case of the current collector 13 of the fuel
electrode 10 to form the oxygen electrode 20.

[0240] Next, the resin sheet having adhesion was prepared, and a channel
was formed with the resin sheet to form the electrolytic solution channel
30 and the fuel channel 40, and the electrolytic solution channel 30 and
the fuel channel 40 were thermal compression bonded to both sides of the
fuel electrode 10.

[0241] Next, the external members 14 and 24 made of the above-described
material were formed, and the fuel inlet 14A and the fuel outlet 14B
configured of, for example, joints made of a resin were arranged in the
external member 14, and the electrolytic solution inlet 24A and the
electrolytic solution outlet 24B configured of, for example, joints made
of a resin were arranged in the external member 24.

[0242] After that, the fuel electrode 10 and the oxygen electrode 20 were
arranged so as to face each other so that the electrolytic solution
channel 30 was arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 was arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 were contained in the external
members 14 and 24.

[0243] Thus, two fuel cell elements 111A and 111B were formed, and stacked
in a vertical direction, and the electrolytic solution channels 30 and
the fuel channels 40 of two fuel cell elements 111A and 111B were
connected in series to each other. That is, the electrolytic solution
outlet 24B of the fuel cell element 111A was connected to the
electrolytic solution inlet 24A of the fuel cell element 111B through the
connection channel 24C configured of a silicone tube, and the fuel outlet
14B of the fuel cell element 111A was connected to the fuel inlet 14A of
the fuel cell element 111B through the connection channel 14C configured
of a silicone tube. Moreover, the separation room 160 was connected to a
midpoint of each of the connection channels 14C and 24C. Thereby, the
fuel cell stack 110 illustrated in FIG. 2 was completed.

[0244] The fuel cell stack 110 was mounted in a system including the
measurement section 120, the control section 130, the electrolytic
solution supply section 140 and the fuel supply section 150 all having
the above-described configurations so as to form the fuel cell stack
system 1 illustrated in FIG. 1. At that time, the electrolytic solution
supply adjustment section 142 and the fuel supply adjustment section 152
were configured of diaphragm type quantitative pumps (manufactured by KNF
Neuberger GmbH). The fuel inlet 14A of the fuel cell element 111A and the
fuel outlet 14B of the fuel cell element 111B were connected to the pump
of the fuel supply adjustment section 152 through the fuel supply line
153 configured of a silicone tube, and the electrolytic solution inlet
24A of the fuel cell element 111A and the electrolytic solution outlet
24B of the fuel cell element 111B were connected to the pump of the
electrolytic solution supply adjustment section 142 through the
electrolytic solution supply line 143 configured of a silicone tube, and
the electrolytic solution F1 and the fuel F2 were supplied to the
electrolytic solution channel 30 and the fuel channel 40 at an arbitrary
flow velocity, respectively. As the electrolytic solution F1, 1M sulfuric
acid was used, and the flow velocity was 1.0 ml/min. As the fuel F2, a
mixed liquid of 5M methanol and 1M sulfuric acid was used, and the flow
velocity was 0.5 ml/min.

[0245] (Evaluation)

[0246] The obtained fuel cell stack system 1 was connected to an
electrochemical measurement system (Multistat 1480 manufactured by
Solartoron Co., Ltd), and the characteristics of the fuel cell system 1
were evaluated. The characteristics of each of the fuel cell elements
111A and 111B and the fuel cell stack 110 when generating electric power
at an open circuit voltage (OCV) in an initial stage of measurement and a
constant current of 1A were examined. The results are illustrated in
FIGS. 26 and 27.

[0247]FIG. 26 illustrates the OCV in the initial state of measurement.
FIG. 26 illustrates a state in which the OCV was maintained for
approximately 180 seconds, and the OCD showed a high value, and
increased. The value of the OCV was 1.3 V or over, so the OCV of each
fuel cell element was 0.65 V or over, and showed a much higher value than
the OCV (approximately 0.4 V to 0.5 V) of a typical DMFC. It was
considered that fuel crossover was prevented by using the electrolytic
solution F1. Moreover, the value of the OCV of the fuel cell stack 110
was approximately twice as high as the value of the OCV of each of the
fuel cell elements 111A and 111B, so it appeared that there was no harm
in connecting the electrolytic solution channels 30 and the fuel channels
40 in series to one another.

[0248] Moreover, it was obvious from FIG. 27 that the characteristics of
the fuel cell stack 110 at a constant current of 1A were stable. That is,
it was found out that when the electrolytic solution channels 30 and the
fuel channels 40 of the plurality of fuel cell elements 111A and the 111B
were connected in series to one another, stability of electric power
generation was allowed to be improved.

Example 2

[0249] As in the case of the above-described second embodiment, the fuel
cell 110A was formed. First, an alloy including platinum (Pt) and
ruthenium (Ru) at a predetermined ratio as a catalyst and a dispersion
solution of a polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a
registered trademark)" manufactured by E. I. du Pont de Nemours and
Company) were mixed at a predetermined ratio to form the catalyst layer
11 of the fuel electrode 10. The catalyst layer 11 was thermal
compression bonded to the diffusion layer 12 made of the above-described
material (HT-2500 manufactured by E-TEK Inc.) for 10 minutes under the
conditions where the temperature was 150° C. and the pressure was
249 kPa. Further, the current collector 13 made of the above-described
material was thermal compression bonded with a hot-melt adhesive or a
resin sheet having adhesion to form the fuel electrode 10.

[0250] Moreover, carbon-supported platinum (Pt) as a catalyst and a
dispersion solution of a polyperfluoroalkyl sulfonic acid-based resin
("Nafion (a registered trademark)" manufactured by E. I. du Pont de
Nemours and Company) were mixed at a predetermined rate to form the
catalyst layer 21 of the oxygen electrode 20. The catalyst layer 21 was
thermal compression bonded to the diffusion layer 22 made of the
above-described material (HT-2500 manufactured by E-TEK Inc.) as in the
case of the catalyst layer 11 of the fuel electrode 10. Further, the
current collector 23 of the above-described material was thermal
compression bonded as in the case of the current collector 13 of the fuel
electrode 10 to form the oxygen electrode 20.

[0251] Next, the substrate 51 configured of the resin sheet having
adhesion was prepared, and the first main channel 52, the second main
channel 53 and the parallel channels 54 illustrated in FIGS. 10 and 11
were formed in the substrate 51, and the ribs 55 were formed in the
inlets 54A and the outlets 54B of the parallel channels 54 to form the
fuel channel 40. Moreover, the electrolytic solution channel 30
illustrated in FIGS. 12 and 13 was formed in the same manner, and the
fuel channel 40 and the electrolytic solution channel 30 were thermal
compression bonded to both sides of the fuel electrode 10. At that time,
18 parallel channels 54 were formed, and the height H0 of each of the
parallel channels 54 was 175 μm, and the height H1 of each of the ribs
55 was changed to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% and 90% of the
height HO of the parallel channel 54.

[0252] Next, the external members 14 and 24 made of the above-described
material were formed, and the fuel inlet 14A and the fuel outlet 14B
configured of, for example, joints made of a resin were arranged in the
external member 14, and the electrolytic solution inlet 24A and the
electrolytic solution outlet 24B configured of, for example, joints made
of a resin were arranged in the external member 24.

[0253] After that, the fuel electrode 10 and the oxygen electrode 20 were
arranged so as to face each other so that the electrolytic solution
channel 30 was arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 was arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 were contained in the external
members 14 and 24.

[0254] The fuel cell 110A was mounted in a system including the
measurement section 120, the control section 130, the electrolytic
solution supply section 140 and the fuel supply section 150 all having
the above-described configurations so as to form the fuel cell system 1A
illustrated in FIG. 8. At that time, the electrolytic solution supply
adjustment section 142 and the fuel supply adjustment section 152 were
configured of diaphragm type quantitative pumps (manufactured by KNF
Neuberger GmbH), and the pumps were directly connected to the
electrolytic solution inlet 24B and the fuel inlet 14A through the
electrolytic solution supply line 143 and the fuel supply line 153
configured of silicone tubes, respectively, and the electrolytic solution
F1 and the fuel F2 were supplied to the electrolytic solution channel 30
and the fuel channel 40 at an arbitrary flow velocity, respectively. As
the electrolytic solution F1, 1M sulfuric acid was used, and the flow
velocity was 1.0 ml/min. As the fuel F2, a mixed liquid of 5M methanol
and 1M sulfuric acid was used, and the flow velocity was 0.5 ml/min.

[0255] (Evaluation)

[0256] The flow velocity ratio distributions in 18 parallel channels 54 in
the obtained fuel cell system 1A were determined. The results are
illustrated in FIG. 28. In FIG. 28, velocity distributions in the
parallel channels 54 when changing the height H1 of the rib 55 based on a
flow velocity ratio 1 were illustrated as a ratio. In addition, channel
numbers 1 to 18 are assigned to parallel channels 54 in order from a side
near the main inlet 52A.

[0257] It was obvious from FIG. 28 that as the height H1 of the rib 55 was
increased relative to the height H0 of the parallel channel 54, the flow
velocity ratio distributions in the parallel channels 54 were reduced,
and in the case where the height H1 was 90% of the height H0, the flow
velocity ratio distributions were allowed to be substantially zero. That
is, it was confirmed that as the height H1 of the rib 55 was increased
relative to the height H0 of the parallel channel 54, the flow velocity
ratio distributions in the parallel channels 54 was reduced, and the fuel
F2 or the electrolytic solution F1 was allowed to uniformly flow through
the parallel channels 54.

Example 3

[0258] The fuel cell systems 1A were formed as in the case of the
above-described Example 2, except that the number N of the parallel
channels 54 was changed to 1, 6, 12 and 18.

[0259] Electric power generation characteristics of the obtained fuel cell
systems 1A were examined. At that time, the height HO and the width of
the parallel channel 54 was 175 μm and 2 mm, respectively, and the
height H1 of the rib 55 was slightly less than 40% of the height H0 of
the parallel channel 54. Moreover, the measurement voltage was 0.3 V, and
the data 180 seconds after the start of electric power generation at a
constant voltage of 0.3 V was taken. The obtained results are illustrated
in FIG. 29.

[0260] It was obvious from FIG. 29 that as the number N of the parallel
channels 54 was increased to 1 (N=1), 6 (N=6), 12 (N=12) and 18 (N=18),
electric power generation characteristics were increased with a
substantially linear relationship. If the fluid does not flow uniformly,
the electric power generation characteristics are not increased with a
linear relationship. That is, it was confirmed that when regions of which
the sectional area was reduced by forming the ribs 55 at the inlet 54A
and the outlet 54B of the parallel channels 54 was arranged, uniformity
of the flow through the parallel channels 54 was improved.

Example 4

[0261] In the following Examples 4 and 5, the fuel cells 110 illustrated
in FIGS. 15 and 16 were formed, and the characteristics thereof were
evaluated. Therefore, referring to FIGS. 8, 15 and 16, like components
will be described using like numerals.

[0262] The fuel cell 110B having the same configuration of that in FIG. 15
was formed. First, an alloy including platinum (Pt) and ruthenium (Ru) at
a predetermined ratio as a catalyst and a dispersion solution of a
polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a registered
trademark)" manufactured by E. I. du Pont de Nemours and Company) were
mixed at a predetermined ratio to form the catalyst layer 11 of the fuel
electrode 10. The catalyst layer 11 was thermal compression bonded to the
diffusion layer 12 made of the above-described material (HT-2500
manufactured by E-TEK Inc.) for 10 minutes under the conditions where the
temperature was 150° C. and the pressure was 249 kPa. Moreover, as
the functional layer 51, a fine porous film made of polyimide with a
thickness of approximately 10 μm to 15 μm was prepared, and the
functional layer 51 was thermal compression bonded to the catalyst layer
11 for 5 minutes under the conditions where the temperature was
150° C. and the pressure was 249 kPa. Further, the current
collector 13 made of the above-described material was thermal compression
bonded with a hot-melt adhesive or a resin sheet having adhesion to form
the fuel electrode 10.

[0263] Moreover, carbon-supported platinum (Pt) as a catalyst and a
dispersion solution of a polyperfluoroalkyl sulfonic acid-based resin
("Nafion (a registered trademark)" manufactured by E. I. du Pont de
Nemours and Company) were mixed at a predetermined rate to form the
catalyst layer 21 of the oxygen electrode 20. The catalyst layer 21 was
thermal compression bonded to the diffusion layer 22 made of the
above-described material (HT-2500 manufactured by E-TEK Inc.) as in the
case of the catalyst layer 11 of the fuel electrode 10. Further, the
current collector 23 of the above-described material was thermal
compression bonded as in the case of the current collector 13 of the fuel
electrode 10 to form the oxygen electrode 20.

[0264] Next, a resin sheet having adhesion was prepared, and the channel
was formed with the resin sheet to form the electrolytic solution channel
30 and the fuel channel 40, and the electrolytic solution channel 30 and
the fuel channel 40 were thermal compression bonded to both sides of the
fuel electrode 10.

[0265] Next, the external members 14 and 24 made of the above-described
material were formed, and the fuel inlet 14A and the fuel outlet 14B
configured of, for example, joints made of a resin were arranged in the
external member 14, and the electrolytic solution inlet 24A and the
electrolytic solution outlet 24B configured of, for example, joints made
of a resin were arranged in the external member 24.

[0266] After that, the fuel electrode 10 and the oxygen electrode 20 were
arranged so as to face each other so that the electrolytic solution
channel 30 was arranged between the fuel electrode 10 and the oxygen
electrode 20 and the fuel channel 40 was arranged outside, and the fuel
electrode 10 and the oxygen electrode 20 were contained in the external
members 14 and 24. Thereby, the fuel cell 110B illustrated in FIG. 15 was
completed.

[0267] The fuel cell 110B was mounted in a system including the
measurement section 120, the control section 130, the electrolytic
solution supply section 140 and the fuel supply section 150 all having
the above-described configurations so as to form the fuel cell system 1A
illustrated in FIG. 8. At that time, the electrolytic solution supply
adjustment section 142 and the fuel supply adjustment section 152 were
configured of diaphragm type quantitative pumps (manufactured by KNF
Neuberger GmbH), and the pumps were directly connected to electrolytic
solution inlet 24A and the fuel inlet 14A through the electrolytic
solution supply line 143 and the fuel supply line 153 configured of
silicone tubes, respectively, and the electrolytic solution F1 and the
fuel F2 were supplied to the electrolytic solution channel 30 and the
fuel channel 40 at an arbitrary flow velocity, respectively. As the
electrolytic solution F1, 1M sulfuric acid was used, and the flow
velocity was 1.0 ml/min. As the fuel F2, a mixed liquid of 5M methanol
and 1M sulfuric acid was used, and the flow velocity was 0.080 ml/min.

[0268] As Comparative Example 1 relative to the example, a fuel cell was
formed as in the case of Example 4 except that the functional layer 51
was not arranged, and a fuel cell system using the fuel cell was formed.

[0269] (Evaluation)

[0270] The obtained fuel cell systems of Example 4 and Comparative Example
1 were connected to an electrochemical measurement system (Multistat 1480
manufactured by Solartoron Co., Ltd) to perform a constant current mode
operation, and the characteristics of the fuel cell systems were
evaluated. As a measurement condition, the current density was
approximately 150 mA/cm2. The result of Comparative Example 1 and
the result of Example 4 are illustrated in FIGS. 30 and 31, respectively.

[0271] The fuel cells operated at a current value at which the generation
of CO2 was visible, so in Comparative Example 1 in which the
functional layer was not included, the influence was obvious. Excess
CO2 was generated as bubbles on the electrolytic solution F1 side,
and these bubbles were not completely removed from the electrolytic
solution channel 30, and exit in the electrolytic solution channel 30,
thereby the flow of the electrolytic solution F1 was disturbed. The
bubbles also affect the proton conductivity of the electrolytic solution
F1, so as illustrated in FIG. 30, in Comparative Example 1,
characteristics were extremely unstable. In the case where CO2 was
generated, and exit in the electrolytic solution channel 30 as bubbles,
the voltage was reduced, and when CO2 bubbles were transferred from
the electrolytic solution channel 30, the voltage was increased.
Therefore, when the CO2 bubbles were allowed to be efficiently
removed from the electrolytic solution channel 30, continuous electric
power generation was allowed without the functional layer, but if
CO2 bubbles were not allowed to be removed from the electrolytic
solution channel 30 on a regular basis, the characteristics was getting
worse.

[0272] On the other hand, in Example 4 in which the functional layer 51
was formed, it was obvious from FIG. 31 that the characteristics were
extremely stable. It was considered that it was because almost all
generated CO2 was released into the fuel F2 as bubbles. That is, it
was confirmed that when the functional layer 51 was arranged on the
catalyst layer 11 of the fuel electrode 10, the direction where the
carbon dioxide bubbles were released was controllable, and the
characteristics were allowed to be stabilized.

Example 5

[0273] The fuel cell 110 having the same configuration as that in FIG. 16
was formed. At that time, while the functional layer 51 was not formed in
the fuel electrode 10, a blend layer of PVDF as a water repellent resin
and a polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a registered
trademark)" manufactured by E. I. du Pont de Nemours and Company) as a
proton conductor was formed on the catalyst layer 21 of the oxygen
electrode 20 as the functional layer 52. The fuel cell 110B was formed as
in the case of Example 4 except for this, and the fuel cell system 1A was
formed.

[0274] As Comparative Example 2 relative to the example, a fuel cell was
formed as in the case of Example 4, except that the functional layer 52
was not arranged, and a fuel cell system was formed using the fuel cell.

[0275] Characteristics of the obtained fuel cell systems of Example 5 and
Comparative Example 2 were evaluated as in the case of the
above-described Example 4 and Comparative Example 1. The result of
Comparative Example 2 and the result of Example 5 are illustrated in
FIGS. 32 and 33, respectively.

[0276] It was obvious from FIGS. 32 and 33 that in Comparative Example 2
in which the functional layer was not arranged, the characteristics were
largely deteriorated for approximately 2 hours, but in Example 5 in which
the functional layer 52 was arranged, deterioration of the
characteristics were less likely to occur, and the electric power
generation was stably maintained for a long time. It was considered that
it was because when the functional layer 52 was arranged on the catalyst
layer 21 of the oxygen electrode 20, overvoltage in the oxygen electrode
20 due to fuel crossover was prevented, and flooding in the oxygen
electrode 20 was prevented. That is, it was confirmed that when the
functional layer 52 was arranged on the catalyst layer 21 of the oxygen
electrode 20, deterioration of the characteristics were preventable, and
long-time electric power generation was allowed.

[0277] In the above-described embodiments and examples, the configurations
of the fuel electrode 10, the oxygen electrode 20, the fuel channel 30
and the electrolytic solution channel 40 are described in detail, but
they may have any other configuration or may be made of any other
material. For example, in the above-described third and fourth
embodiments, the fuel channel 30 may be configured of a sheet made of a
porous material or the like in addition to a channel formed by processing
the resin sheet described in the above-described first embodiment and
examples.

[0278] Moreover, for example, in the above-described first embodiment and
examples, the case where a plurality of fuel cell elements 111 are
stacked in a vertical direction (a stacking direction) to form the fuel
cell stack 110 is described; however, for example, as illustrated in FIG.
34, the invention is applicable to the case where a plurality of fuel
cell elements 111 are stacked in a horizontal direction (a stack plane
direction) to form the fuel cell stack 110.

[0279] Further, as illustrated in FIG. 35, the gas-liquid separation film
60 described in the fourth embodiment may be arranged between the fuel
channel 40 and the fuel electrode 10.

[0280] In addition, in the above-described second embodiment and examples,
the case where regions of which sectional areas are reduced by forming
the ribs 55 in both of the inlet 54A and the outlet 54B of the parallel
channel 54 are arranged is described; however, the rib 55 may be arranged
either or both of the inlet 54A and the outlet 54B. For example, as
illustrated in FIG. 36, the rib 55 may be arranged only in the inlet 54A,
or as illustrated in FIG. 37, the rib 55 may be arranged only in the
outlet 54B. In addition, FIGS. 36 and 37 illustrate modification examples
of the fuel channel 40, but the same modification examples are applicable
to the electrolytic solution channel 30.

[0281] Moreover, in the above-described second embodiment and examples,
the case where the case where the ribs 55 are arranged in all of the
parallel channels 54 is described; however, the rib 55 may be arranged
one or more of the parallel channels 54.

[0282] Further, in the above-described second embodiment and examples, the
case where the heights H1 of the ribs 55 in all of the parallel channels
54 are equal to one another is described; however, the height H1 of the
rib 55 may differ in each of the parallel channels 54.

[0283] Further, in the above-described second embodiment and examples, the
case where the rib 55 is arranged in a lower part of the parallel channel
54 is described; however, as illustrated in FIG. 38(A), the rib 55 may be
formed in an upper part of the parallel channel 54, or as illustrated in
FIG. 38(B), the rib 55 may be arranged in one or both of a right part and
a left part of the parallel channel 54, or as illustrated in FIG. 38(C),
the rib 55 may be formed in all of the upper, lower, right and left parts
of the parallel channel 54.

[0284] In addition, instead of the electrolytic solution channel 40
described in the above-described second embodiment and examples, as
illustrated in FIG. 39, an electrolyte film 70 made of a
polyperfluoroalkyl sulfonic acid-based resin ("Nafion (a registered
trademark)" manufactured by E. I. du Pont de Nemours and Company) or any
other resin having proton conductivity may be arranged between the fuel
electrode 10 and the oxygen electrode 20.

[0285] Moreover, also in the above-described second embodiment, as
illustrated in FIG. 40, the gas-liquid separation film 60 described in
the fourth embodiment may be arranged between the fuel channel 30 and the
fuel electrode 10.

[0286] Further, for example, in the above-described second embodiment and
examples, the case where the electrolytic solution F1 circulates between
the fuel cell 110 and the electrolytic solution supply section 140 is
described; however, the electrolytic solution F1 may not circulate and
remain stationary between the fuel electrode 10 and the oxygen electrode
20.

[0287] In addition, for example, in the above-described second embodiment
and examples, one fuel cell 110A is described as an example; however, the
invention is applicable to a fuel cell stack in which a plurality of fuel
cells 110A are stacked in a vertical direction (a stacking direction) or
a horizontal direction (a stack plane direction), and the invention is
extremely effective to reduce the thickness and the size of the fuel cell
stack.

[0288] Moreover, in the above-described second embodiment and examples,
the case where the channel structure of the invention is applied to the
fuel channel 30 and the electrolytic solution channel 40 of the fuel cell
110A is described; however, the channel structure of the invention is
widely applicable to applications for flowing a fluid through parallel
channels such as a boiler, a radiator or a concentration sensor.

[0289] Further, for example, in the above-described third and fourth
embodiments and examples, the case where the electrolytic solution F1 is
in a state in which the electrolytic solution F1 consistently flows
during electric power generation is described; however, the invention is
widely applicable to fuel cells using a liquid electrolyte such as a fuel
cell using the electrolytic solution F1 in a stationary state.

[0290] In addition, for example, in the above-described third and fourth
embodiments and examples, the case where one fuel cell 110 is included is
described; however, the invention is applicable to the case where a fuel
cell stack is configured by stacking a plurality of fuel cells 110 in a
vertical direction (a stacking direction) or a horizontal direction (in a
stack plane direction).

[0291] Moreover, for example, the material and the thickness of each
component, a bonding method, electric power generation conditions in the
fuel cell stack 11 and the like are not limited to those described in the
above-described embodiments and examples, and any other material, any
other thickness and any other bonding method may be used, and any other
electric power generation conditions may be used.

[0292] Further, for example, in the above-described embodiments and
examples, the configurations of the fuel electrode 10, the oxygen
electrode 20, the fuel channel 30 and the electrolytic solution channel
40 are described in detail; however, they may have any other
configuration or may be made of any other material.

[0293] In addition, in the above-described embodiments, the case where the
fuel F2 is supplied from the fuel supply section 150 to the fuel
electrode 10 is described; however, the fuel electrode 10 may be of a
sealed type, and the fuel F2 may be supplied as necessary.

[0294] Moreover, for example, the fuel F2 may be any other liquid fuel
such as ethanol or dimethyl ether in addition to methanol. The
electrolytic solution F1 is not specifically limited as long as the
electrolytic solution F1 has proton (H+) conductivity, and examples of
the electrolytic solution F1 include a phosphoric acid and an ionic
liquid in addition to the sulfuric acid.

[0295] Further, the embodiments are not limited to a fuel cell using a
liquid fuel, and is applicable to a fuel cell using a substance such as
hydrogen other than a liquid fuel as a fuel.

[0296] In addition, in the above-described embodiments and examples, air
is supplied to the oxygen electrode 20 by natural ventilation; however,
air may be forcefully supplied using a pump or the like. In this case,
oxygen or a gas including oxygen may be supplied instead of air.

[0297] Moreover, in the above-described embodiments and examples, the case
where in the fuel cell 110, the fuel electrode 10 and the oxygen
electrode 20 are arranged so as to face each other so that the
electrolytic solution channel 30 is arranged between the fuel electrode
10 and the oxygen electrode 20 and the fuel channel 40 is arranged
outside is described; however, the invention is applicable to a fuel cell
system including a fuel cell with any other configuration.

[0298] It should be understood that various changes and modifications to
the presently preferred embodiments described herein will be apparent to
those skilled in the art. Such changes and modifications can be made
without departing from the spirit and scope of the present subject matter
and without diminishing its intended advantages. It is therefore intended
that such changes and modifications be covered by the appended claims.